Methods and apparatus for treatment of atrial fibrillation

ABSTRACT

Apparatus and methods for the treatment of atrial fibrillation are described herein where tissue to be ablated may be monitored under direct visualization. Such a system may include a deployment catheter and an attached imaging hood deployable into an expanded configuration. In use, the imaging hood is placed against or adjacent to the tissue to be imaged in a body lumen that is normally filled with an opaque bodily fluid such as blood. A translucent or transparent fluid can be pumped into the imaging hood until the fluid displaces any blood leaving a clear region of tissue to be imaged via an imaging element in the deployment catheter. An ablation probe may be advanced into the contained region where the tissue may be ablated and monitored for changes in color as well as appropriate positioning.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to the following U.S.Prov. Pat. App. Ser. Nos. 60/806,923; 60/806,924; and 60/806,926 eachfiled Jul. 10, 2006; this is also a continuation-in-part of U.S. patentapplication Ser. No. 11/259,498 filed Oct. 25, 2005, which claimspriority to U.S. Prov. Pat. App. Ser. No. 60/649,246 filed Feb. 2, 2005.Each application is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to medical devices used foraccessing, visualizing, and/or treating regions of tissue within a body.More particularly, the present invention relates to methods andapparatus for accessing, visualizing, and/or treating conditions such asatrial fibrillation within a patient heart.

BACKGROUND OF THE INVENTION

Conventional devices for visualizing interior regions of a body lumenare known. For example, ultrasound devices have been used to produceimages from within a body in vivo. Ultrasound has been used both withand without contrast agents, which typically enhance ultrasound-derivedimages.

Other conventional methods have utilized catheters or probes havingposition sensors deployed within the body lumen, such as the interior ofa cardiac chamber. These types of positional sensors are typically usedto determine the movement of a cardiac tissue surface or the electricalactivity within the cardiac tissue. When a sufficient number of pointshave been sampled by the sensors, a “map” of the cardiac tissue may begenerated.

Another conventional device utilizes an inflatable balloon which istypically introduced intravascularly in a deflated state and theninflated against the tissue region to be examined. Imaging is typicallyaccomplished by an optical fiber or other apparatus such as electronicchips for viewing the tissue through the membrane(s) of the inflatedballoon. Moreover, the balloon must generally be inflated for imaging.Other conventional balloons utilize a cavity or depression formed at adistal end of the inflated balloon. This cavity or depression is pressedagainst the tissue to be examined and is flushed with a clear fluid toprovide a clear pathway through the blood.

However, such imaging balloons have many inherent disadvantages. Forinstance, such balloons generally require that the balloon be inflatedto a relatively large size which may undesirably displace surroundingtissue and interfere with fine positioning of the imaging system againstthe tissue. Moreover, the working area created by such inflatableballoons are generally cramped and limited in size. Furthermore,inflated balloons may be susceptible to pressure changes in thesurrounding fluid. For example, if the environment surrounding theinflated balloon undergoes pressure changes, e.g., during systolic anddiastolic pressure cycles in a beating heart, the constant pressurechange may affect the inflated balloon volume and its positioning toproduce unsteady or undesirable conditions for optimal tissue imaging.

Accordingly, these types of imaging modalities are generally unable toprovide desirable images useful for sufficient diagnosis and therapy ofthe endoluminal structure, due in part to factors such as dynamic forcesgenerated by the natural movement of the heart. Moreover, anatomicstructures within the body can occlude or obstruct the image acquisitionprocess. Also, the presence and movement of opaque bodily fluids such asblood generally make in vivo imaging of tissue regions within the heartdifficult.

Other external imaging modalities are also conventionally utilized. Forexample, computed tomography (CT) and magnetic resonance imaging (MRI)are typical modalities which are widely used to obtain images of bodylumens such as the interior chambers of the heart. However, such imagingmodalities fail to provide real-time imaging for intra-operativetherapeutic procedures. Fluoroscopic imaging, for instance, is widelyused to identify anatomic landmarks within the heart and other regionsof the body. However, fluoroscopy fails to provide an accurate image ofthe tissue quality or surface and also fails to provide forinstrumentation for performing tissue manipulation or other therapeuticprocedures upon the visualized tissue regions. In addition, fluoroscopyprovides a shadow of the intervening tissue onto a plate or sensor whenit may be desirable to view the intraluminal surface of the tissue todiagnose pathologies or to perform some form of therapy on it.

Thus, a tissue imaging system which is able to provide real-time in vivoimages of tissue regions within body lumens such as the heart throughopaque media such as blood and which also provide instruments fortherapeutic procedures upon the visualized tissue are desirable.

BRIEF SUMMARY OF THE INVENTION

A tissue imaging and manipulation apparatus that may be utilized forprocedures within a body lumen, such as the heart, in whichvisualization of the surrounding tissue is made difficult, if notimpossible, by medium contained within the lumen such as blood, isdescribed below. Generally, such a tissue imaging and manipulationapparatus comprises an optional delivery catheter or sheath throughwhich a deployment catheter and imaging hood may be advanced forplacement against or adjacent to the tissue to be imaged.

The deployment catheter may define a fluid delivery lumen therethroughas well as an imaging lumen within which an optical imaging fiber orassembly may be disposed for imaging tissue. When deployed, the imaginghood may be expanded into any number of shapes, e.g., cylindrical,conical as shown, semi-spherical, etc., provided that an open area orfield is defined by the imaging hood. The open area is the area withinwhich the tissue region of interest may be imaged. The imaging hood mayalso define an atraumatic contact lip or edge for placement or abutmentagainst the tissue region of interest. Moreover, the distal end of thedeployment catheter or separate manipulatable catheters may bearticulated through various controlling mechanisms such as push-pullwires manually or via computer control

The deployment catheter may also be stabilized relative to the tissuesurface through various methods. For instance, inflatable stabilizingballoons positioned along a length of the catheter may be utilized, ortissue engagement anchors may be passed through or along the deploymentcatheter for temporary engagement of the underlying tissue.

In operation, after the imaging hood has been deployed, fluid may bepumped at a positive pressure through the fluid delivery lumen until thefluid fills the open area completely and displaces any blood from withinthe open area. The fluid may comprise any biocompatible fluid, e.g.,saline, water, plasma, Fluorinert™, etc., which is sufficientlytransparent to allow for relatively undistorted visualization throughthe fluid. The fluid may be pumped continuously or intermittently toallow for image capture by an optional processor which may be incommunication with the assembly.

In an exemplary variation for imaging tissue surfaces within a heartchamber containing blood, the tissue imaging and treatment system maygenerally comprise a catheter body having a lumen defined therethrough,a visualization element disposed adjacent the catheter body, thevisualization element having a field of view, a transparent fluid sourcein fluid communication with the lumen, and a barrier or membraneextendable from the catheter body to localize, between the visualizationelement and the field of view, displacement of blood by transparentfluid that flows from the lumen, and a piercing instrument translatablethrough the displaced blood for piercing into the tissue surface withinthe field of view.

The imaging hood may be formed into any number of configurations and theimaging assembly may also be utilized with any number of therapeutictools which may be deployed through the deployment catheter.

More particularly in certain variations, the tissue visualization systemmay comprise components including the imaging hood, where the hood mayfurther include a membrane having a main aperture and additionaloptional openings disposed over the distal end of the hood. Anintroducer sheath or the deployment catheter upon which the imaging hoodis disposed may further comprise a steerable segment made of multipleadjacent links which are pivotably connected to one another and whichmay be articulated within a single plane or multiple planes. Thedeployment catheter itself may be comprised of a multiple lumenextrusion, such as a four-lumen catheter extrusion, which is reinforcedwith braided stainless steel fibers to provide structural support. Theproximal end of the catheter may be coupled to a handle for manipulationand articulation of the system.

In additional variations of the imaging hood and deployment catheter,the various assemblies may be configured in particular for treatingconditions such as atrial fibrillation while under direct visualization.In particular, the devices and assemblies may be configured tofacilitate the application of energy to the underlying tissue in acontrolled manner while directly visualizing the tissue to monitor aswell as confirm appropriate treatment. Generally, the imaging andmanipulation assembly may be advanced intravascularly into the patient'sheart, e.g., through the inferior vena cava and into the right atriumwhere the hood maybe deployed and positioned against the atrial septumand the hood may be infused with saline to clear the blood from withinto view the underlying tissue surface.

Once the hood has been desirably positioned over the fossa ovalis, apiercing instrument, e.g., a hollow needle, may be advanced from thecatheter and through the hood to pierce through the atrial septum untilthe left atrium has been accessed. A guidewire may then be advancedthrough the piercing instrument and introduced into the left atrium,where it may be further advanced into one of the pulmonary veins. Withthe guidewire crossing the atrial septum into the left atrium, thepiercing instrument may be withdrawn or the hood may be furtherretracted into its low profile configuration and the catheter and sheathmay be optionally withdrawn as well while leaving the guidewire in placecrossing the atrial septum. A dilator may be advanced along theguidewire to dilate the opening through the atrial septum to provide alarger transseptal opening for the introduction of the hood and otherinstruments into the left atrium. Further examples of methods anddevices for transseptal access are shown and described in further detailin commonly owned U.S. patent application Ser. No. 11/763,399 filed Jun.14, 2007, which is incorporated herein by reference in its entirety.Those transseptal access methods and devices may be fully utilized withthe methods and devices described herein, as practicable.

With the hood advanced into and expanded within the left atrium, thedeployment catheter and/or hood may be articulated to be placed intocontact with or over the ostia of the pulmonary veins. Once the hood hasbeen desirably positioned along the tissue surrounding the pulmonaryveins, the open area within the hood may be cleared of blood with thetranslucent or transparent fluid for directly visualizing the underlyingtissue such that the tissue may be ablated. An ablation probe, which maybe configured in a number of different shapes, may be advanced into andthrough the hood interior while under direct visualization and broughtinto contact against the tissue region of interest for ablationtreatment. One or more of the ostia may be ablated either partially orentirely around the opening to create a conduction block. In performingthe ablation, the hood may be pressed against the tissue utilizing thesteering and/or articulation capabilities of the deployment catheter aswell as the sheath. Alternatively and/or additionally, a negativepressure may be created within the hood by drawing in the transparentfluid back through the deployment catheter to create a seal with respectto the tissue surface. Moreover, the hood may be further approximatedagainst the tissue by utilizing one or more tissue graspers which may beadvanced through the hood, such as helical tissue graspers, totemporarily adhere onto the tissue and create a counter-traction force.

Because the hood allows for direct visualization of the underlyingtissue in vivo, the hood may be used to visually confirm that theappropriate regions of tissue have been ablated and/or that the tissuehas been sufficiently ablated. Visual monitoring and confirmation may beaccomplished in real-time during a procedure or after the procedure hasbeen completed. Additionally, the hood may be utilized post-operativelyto image tissue which has been ablated in a previous procedure todetermine whether appropriate tissue ablation had been accomplished.

Generally, in ablating the underlying visualized tissue with theablation probe, one or more ostia of the pulmonary veins or other tissueregions within the left atrium may be ablated by moving the ablationprobe within the area defined by the hood and/or moving the hood itselfto tissue regions to be treated, such as around the pulmonary veinostium. Visual monitoring of the ablation procedure not only providesreal-time visual feedback to maintain the probe-to-tissue contact, butalso provides real-time color feedback of the ablated tissue surface asan indicator when irreversible tissue damage may occur. This colorchange during lesion formation may be correlated to parameters such asimpedance, time of ablation, power applied, etc.

Moreover, real-time visual feedback also enables the user to preciselyposition and move the ablation probe to desired locations along thetissue surface fore creating precise lesion patterns. Additionally, thevisual feedback also provides a safety mechanism by which the user canvisually detect endocardial disruptions and/or complications, such assteam formation or bubble formation. In the event that an endocardialdisruption or complication occurs, any resulting tissue debris can becontained within the hood and removed from the body by suctioning thecontents of the hood proximally into the deployment catheter before thedebris is released into the body. The hood also provides a relativelyisolated environment with little or no blood so as to reduce any risk ofcoagulation. The displacement fluid may also provide a cooling mechanismfor the tissue surface to prevent over-heating by introducing andpurging the saline into and through the hood.

Once the ablation procedure is finished, the hood may be utilized tovisually evaluate the post-ablation lesion for contiguous lesionformation and/or for visual confirmation of any endocardial disruptionsby identifying cratering or coagulated tissue or charred tissue. Ifdetermined desirable or necessary upon visual inspection, the tissuearea around the pulmonary vein ostium or other tissue region may beablated again without having to withdraw or re-introduce the ablationinstrument.

To ablate the tissue visualized within hood, a number of variousablation instruments may be utilized. For example, ablation probe havingat least one ablation electrode utilizing, e.g., radio-frequency (RF),microwave, ultrasound, laser, cryo-ablation, etc., may be advancedthrough deployment catheter and into the open area of the hood.Alternatively, variously configured ablation probes may be utilized,such as linear or circularly-configured ablation probes depending uponthe desired lesion pattern and the region of tissue to be ablated.Moreover, the ablation electrodes may be placed upon the various regionsof the hood as well.

Ablation treatment under direct visualization may also be accomplishedutilizing alternative visualization catheters which may additionallyprovide for stability of the catheter with respect to the dynamicallymoving tissue and blood flow. For example, one or more grasping supportmembers may be passed through the catheter and deployed from the hood toallow for the hood to be walked or moved along the tissue surfaces ofthe heart chambers. Other variations may also utilize intra-atrialballoons which occupy a relatively large volume of the left atrium andprovide direct visualization of the tissue surfaces.

A number of safety mechanisms may also be utilized. For instance, toprevent the inadvertent piercing or ablation of an ablation instrumentfrom injuring adjacent tissue structures, such as the esophagus, a lightsource or ultrasound transducer may be attached to or through a catheterwhich can be inserted transorally into the esophagus and advanced untilthe catheter light source is positioned proximate to or adjacent to theheart. During an intravascular ablation procedure in the left atrium,the operator may utilize the imaging element to visually (or otherwisesuch as through ultrasound) detect the light source in the form of abackground glow behind the tissue to be ablated as an indication of thelocation of the esophagus. Another safety measure which may be utilizedduring tissue ablation is the utilization of color changes in the tissuebeing ablated. One particular advantage of a direct visualization systemdescribed herein is the ability to view and monitor the tissue inreal-time and in detailed color.

The devices and methods described herein provide a number of advantagesover previous devices. For instance, ablating the pulmonary vein ostiaand/or endocardiac tissue under direct visualization provides real-timevisual feedback on contact between the ablation probe and the tissuesurface as well as visual feedback on the precise position and movementof the ablation probe to create desired lesion patterns.

Real-time visual feedback is also provided for confirming a position ofthe hood within the atrial chamber itself by visualizing anatomicallandmarks, such as a location of a pulmonary vein ostium or a leftatrial appendage, a left atrial septum, etc.

Real-time visual feedback is further provided for the early detection ofendocardiac disruptions and/or complications, such as visual detectionof steam or bubble formation. Real-time visual feedback is additionallyprovided for color feedback of the ablated endocardiac tissue as anindicator when irreversible tissue damage occurs by enabling thedetection of changes in the tissue color.

Moreover, the hood itself provides a relatively isolated environmentwith little or no blood so as to reduce any risk of coagulation. Thedisplacement fluid may also provide a cooling mechanism for the tissuesurface to prevent over-heating.

Once the ablation is completed, direct visualization further providesthe capability for visually inspecting for contiguous lesion formationas well as inspecting color differences of the tissue surface. Also,visual inspection of endocardiac disruptions and/or complications ispossible, for example, inspecting the ablated tissue for visualconfirmation for the presence of tissue craters or coagulated blood onthe tissue.

If endocardiac disruptions and/or complications are detected, the hoodalso provides a barrier or membrane for containing the disruption andrapidly evacuating any tissue debris. Moreover, the hood provides forthe establishment of stable contact with the ostium of the pulmonaryvein or other targeted tissue, for example, by the creation of negativepressure within the space defined within the hood for drawing in orsuctioning the tissue to be ablated against the hood for secure contact.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a side view of one variation of a tissue imaging apparatusduring deployment from a sheath or delivery catheter.

FIG. 1B shows the deployed tissue imaging apparatus of FIG. 1A having anoptionally expandable hood or sheath attached to an imaging and/ordiagnostic catheter.

FIG. 1C shows an end view of a deployed imaging apparatus.

FIGS. 1D to 1F show the apparatus of FIGS. 1A to 1C with an additionallumen, e.g., for passage of a guidewire therethrough.

FIGS. 2A and 2B show one example of a deployed tissue imager positionedagainst or adjacent to the tissue to be imaged and a flow of fluid, suchas saline, displacing blood from within the expandable hood.

FIG. 3A shows an articulatable imaging assembly which may be manipulatedvia push-pull wires or by computer control.

FIGS. 3B and 3C show steerable instruments, respectively, where anarticulatable delivery catheter may be steered within the imaging hoodor a distal portion of the deployment catheter itself may be steered.

FIGS. 4A to 4C show side and cross-sectional end views, respectively, ofanother variation having an off-axis imaging capability.

FIG. 5 shows an illustrative view of an example of a tissue imageradvanced intravascularly within a heart for imaging tissue regionswithin an atrial chamber.

FIGS. 6A to 6C illustrate deployment catheters having one or moreoptional inflatable balloons or anchors for stabilizing the deviceduring a procedure.

FIGS. 7A and 7B illustrate a variation of an anchoring mechanism such asa helical tissue piercing device for temporarily stabilizing the imaginghood relative to a tissue surface.

FIG. 7C shows another variation for anchoring the imaging hood havingone or more tubular support members integrated with the imaging hood;each support members may define a lumen therethrough for advancing ahelical tissue anchor within.

FIG. 8A shows an illustrative example of one variation of how a tissueimager may be utilized with an imaging device.

FIG. 8B shows a further illustration of a hand-held variation of thefluid delivery and tissue manipulation system.

FIGS. 9A to 9C illustrate an example of capturing several images of thetissue at multiple regions.

FIGS. 10A and 10B show charts illustrating how fluid pressure within theimaging hood may be coordinated with the surrounding blood pressure; thefluid pressure in the imaging hood may be coordinated with the bloodpressure or it may be regulated based upon pressure feedback from theblood.

FIG. 11A shows a side view of another variation of a tissue imagerhaving an imaging balloon within an expandable hood.

FIG. 11B shows another variation of a tissue imager utilizing atranslucent or transparent imaging balloon.

FIG. 12A shows another variation in which a flexible expandable ordistensible membrane may be incorporated within the imaging hood toalter the volume of fluid dispensed.

FIGS. 12B and 12C show another variation in which the imaging hood maybe partially or selectively deployed from the catheter to alter the areaof the tissue being visualized as well as the volume of the dispensedfluid.

FIGS. 13A and 13B show exemplary side and cross-sectional views,respectively, of another variation in which the injected fluid may bedrawn back into the device for minimizing fluid input into a body beingtreated.

FIGS. 14A to 14D show various configurations and methods for configuringan imaging hood into a low-profile for delivery and/or deployment.

FIGS. 15A and 15B show an imaging hood having an helically expandingframe or support.

FIGS. 16A and 16B show another imaging hood having one or more hoodsupport members, which are pivotably attached at their proximal ends todeployment catheter, integrated with a hood membrane.

FIGS. 17A and 17B show yet another variation of the imaging hood havingat least two or more longitudinally positioned support memberssupporting the imaging hood membrane where the support members aremovable relative to one another via a torquing or pulling or pushingforce.

FIGS. 18A and 18B show another variation where a distal portion of thedeployment catheter may have several pivoting members which form atubular shape in its low profile configuration.

FIGS. 19A and 19B show another variation where the distal portion ofdeployment catheter may be fabricated from a flexible metallic orpolymeric material to form a radially expanding hood.

FIGS. 20A and 20B show another variation where the imaging hood may beformed from a plurality of overlapping hood members which overlie oneanother in an overlapping pattern.

FIGS. 21A and 21B show another example of an expandable hood which ishighly conformable against tissue anatomy with varying geography.

FIG. 22A shows yet another example of an expandable hood having a numberof optional electrodes placed about the contact edge or lip of the hoodfor sensing tissue contact or detecting arrhythmias.

FIG. 22B shows another variation for conforming the imaging hood againstthe underlying tissue where an inflatable contact edge may be disposedaround the circumference of the imaging hood.

FIG. 23 shows a variation of the system which may be instrumented with atransducer for detecting the presence of blood seeping back into theimaging hood.

FIGS. 24A and 24B show variations of the imaging hood instrumented withsensors for detecting various physical parameters; the sensors may beinstrumented around the outer surface of the imaging hood and alsowithin the imaging hood.

FIGS. 25A and 25B show a variation where the imaging hood may have oneor more LEDs over the hood itself for providing illumination of thetissue to be visualized.

FIGS. 26A and 26B show another variation in which a separateillumination tool having one or more LEDs mounted thereon may beutilized within the imaging hood.

FIG. 27 shows one example of how a therapeutic tool may be advancedthrough the tissue imager for treating a tissue region of interest.

FIG. 28 shows another example of a helical therapeutic tool for treatingthe tissue region of interest.

FIG. 29 shows a variation of how a therapeutic tool may be utilized withan expandable imaging balloon.

FIGS. 30A and 30B show alternative configurations for therapeuticinstruments which may be utilized; one variation is shown having anangled instrument arm and another variation is shown with an off-axisinstrument arm.

FIGS. 31A to 31C show side and end views, respectively, of an imagingsystem which may be utilized with an ablation probe.

FIGS. 32A and 32B show side and end views, respectively, of anothervariation of the imaging hood with an ablation probe, where the imaginghood may be enclosed for regulating a temperature of the underlyingtissue.

FIGS. 33A and 33B show an example in which the imaging fluid itself maybe altered in temperature to facilitate various procedures upon theunderlying tissue.

FIGS. 34A and 34B show an example of a laser ring generator which may beutilized with the imaging system and an example for applying the laserring generator within the left atrium of a heart for treating atrialfibrillation.

FIGS. 35A to 35C show an example of an extendible cannula generallycomprising an elongate tubular member which may be positioned within thedeployment catheter during delivery and then projected distally throughthe imaging hood and optionally beyond.

FIGS. 36A and 36B show side and end views, respectively, of an imaginghood having one or more tubular support members integrated with the hoodfor passing instruments or tools therethrough for treatment upon theunderlying tissue.

FIGS. 37A and 37B illustrate how an imaging device may be guided withina heart chamber to a region of interest utilizing a lighted probepositioned temporarily within, e.g., a lumen of the coronary sinus.

FIGS. 38A and 38B show an imaging hood having a removable disk-shapedmember for implantation upon the tissue surface.

FIGS. 39A to 39C show one method for implanting the removable disk ofFIGS. 38A and 38B.

FIGS. 40A and 40B illustrate an imaging hood having a deployable anchorassembly attached to the tissue contact edge and an assembly view of theanchors and the suture or wire connected to the anchors, respectively

FIGS. 41A to 41D show one method for deploying the anchor assembly ofFIGS. 40A and 40B for closing an opening or wound.

FIG. 42 shows another variation in which the imaging system may befluidly coupled to a dialysis unit for filtering a patient's blood.

FIGS. 43A and 43B show a variation of the deployment catheter having afirst deployable hood and a second deployable hood positioned distal tothe first hood; the deployment catheter may also have a side-viewingimaging element positioned between the first and second hoods forimaging tissue between the expanded hoods.

FIGS. 44A and 44B show side and end views, respectively, of a deploymentcatheter having a side-imaging balloon in an un-inflated low-profileconfiguration.

FIGS. 45A to 45C show side, top, and end views, respectively, of theinflated balloon of FIGS. 44A and 44B defining a visualization field inthe inflated balloon.

FIGS. 46A and 46B show side and cross-sectional end views, respectively,for one method of use in visualizing a lesion upon a vessel wall withinthe visualization field of the inflated balloon from FIGS. 45A to 45C.

FIGS. 47A to 470 illustrate an example for intravascularly advancing theimaging and manipulation catheter into the heart and into the leftatrium for ablating tissue around the ostia of the pulmonary veins forthe treatment of atrial fibrillation.

FIGS. 48A and 48B illustrate partial cross-sectional views of a hoodwhich is advanced into the left atrium to examine discontiguous lesions.

FIG. 49A shows a perspective view of a variation of the transmurallesion ablation device with, in this variation, a single RF ablationprobe inserted through the working channel of the tissue visualizationcatheter.

FIG. 49B shows a side view of the device performing tissue ablationwithin the hood under real time visualization.

FIG. 49C shows the perspective view of the device performing tissueablation within the hood under real time visualization.

FIG. 50A shows a perspective view of a variation of the device when anangled ablation probe is used for linear transmural lesion formation.

FIG. 50B shows a perspective view of another variation of the devicewhen a circular ablation probe is used for circular transmural lesionformation.

FIG. 51A shows a perspective view of another variation of the transmurallesion ablation device with a circularly-shaped RF electrode endeffector placed on the outer circumference of an expandable membranecovering the hood of the tissue visualization catheter.

FIG. 51B shows a perspective view of another variation of an expandableballoon also with a circularly-shaped RF electrode end effector andwithout the hood.

FIG. 52 shows a perspective view of another variation of the transmurallesion ablation device with RF electrodes disposed circumferentiallyaround the contact lip or edge of the hood.

FIGS. 53A and 53B show perspective and side views, respectively, ofanother variation of the transmural lesion ablation device with anablation probe positioned within the hood which also includes at leastone layer of a transparent elastomeric membrane over the distal openingof the hood.

FIG. 54A shows a perspective view of another variation of the transmurallesion ablation device having an expandable linear ablation electrodestrip inserted through the working channel of the tissue visualizationcatheter.

FIG. 54B shows the perspective view of the device with the linearablation electrode strip in its expanded configuration.

FIGS. 55A and 55B illustrate perspective views of another variationwhere a laser probe, e.g., an optical fiber bundle coupled to a lasergenerator, may be inserted through the work channel of the tissuevisualization catheter and activated for ablation treatment.

FIG. 55C shows the device of FIGS. 55A and 55B performing tissueablation or transmural lesion formation under direct visualization whileworking within the hood of the visualization catheter apparatus.

FIG. 56 shows a partial cross-sectional view of the tissue visualizationcatheter with an inflated occlusion balloon to temporarily occlude bloodflow through the pulmonary vein while viewing the pulmonary vein'sostia.

FIG. 57 shows a perspective view of first and second tissue graspersdeployed through the hood for facilitating movement of the hood alongthe tissue surface.

FIGS. 58A to 58C illustrate the tissue visualization catheter navigatingaround a body lumen, such as the left atrium of the heart, utilizing twotissue graspers to “walk” the catheter along the tissue surface.

FIG. 59 shows a partial cross-sectional view of the tissue visualizationcatheter in a retroflexed position for accessing the right inferiorpulmonary vein ostium.

FIG. 60 show a partial cross-sectional view of the tissue visualizationcatheter intravascularly accessing the left atrium via a trans-femoralintroduction through the aorta, the aortic valve, the left ventricle,and into the left atrium.

FIG. 61A shows a side view of the tissue visualization catheterretroflexed at a tight angle accessing the right inferior pulmonary veinostium with a first tissue grasper and length of wire or sutureconfigured as a pulley mechanism.

FIG. 61B illustrates the tissue visualization catheter pulling itself toaccess the right inferior PV ostium at a tight angle using a suturepulley mechanism.

FIG. 61C illustrates the tissue visualization catheter prior to thesuture being tensioned.

FIG. 61D illustrates the tissue visualization catheter being moved andapproximated towards the ostium as the suture is tensioned.

FIG. 62A shows a partial cross-sectional view of a tissue visualizationcatheter having an intra-atrial balloon inflated within the left atrium.

FIG. 62B shows the partial cross-sectional view with a fiberscopeintroduced into the balloon interior.

FIG. 62C shows the partial cross-sectional view with the fiberscopeadvancing and articulating within the balloon.

FIG. 62D shows the partial cross-sectional view of the intra-atrialballoon having radio-opaque fiducial markers and an ablation probedeployed within the balloon.

FIG. 63 shows a detail side view of an ablation probe deployed withinthe balloon and penetrating through the balloon wall.

FIGS. 64A and 64B show perspective views of ablation needles deployablefrom a retracted position to a deployed position.

FIG. 64C shows the perspective view of an ablation needle having abipolar electrode configuration.

FIG. 65A to 65E illustrate a stabilizing catheter accessing the leftatrium with a stabilizing balloon deployed in the right atrium andexamples of the articulation and translation capabilities for directingthe hood towards the tissue region to be treated.

FIG. 66A to 66E illustrate another variation of a stabilizing catheteraccessing the left atrium with proximal and distal stabilizing balloonsdeployed about the atrial septum and examples of the articulation andtranslation capabilities for directing the hood towards the tissueregion to be treated.

FIG. 67A to 67F illustrate another variation of a stabilizing catheteraccessing the left atrium with a combination of proximal and distalstabilizing balloons deployed about the atrial septum and anintra-atrial balloon expanded within the left atrium with a hollowneedle for piercing through the balloon and deploying the hood externalto the balloon.

FIG. 68A illustrates a side view of the tissue visualization catheterdeploying an intra-atrial balloon with an articulatable imager capturingmultiple images representing different segments of the heart chamberwall from different angles.

FIG. 68B schematically illustrates the mapping of the multiple capturedimages processed to create a panoramic visual map of the heart chamber.

FIG. 69A shows a partial cross-sectional view of the tissuevisualization catheter in the left atrium performing RF ablation, with alight source or ultrasound crystal source inserted transorally into theesophagus to prevent esophageal perforation.

FIGS. 69B and 69C illustrate the image viewed by the user prior to theablation probe being activated.

FIGS. 69D and 69E illustrate the image viewed by the user of the ablatedtissue changing color as the ablation probe heats the underlying tissue.

FIGS. 69F and 69G illustrate the image viewed by the user of anendocardiac disruption and the resulting tissue debris captured orcontained within the hood.

FIG. 69H illustrates the evacuation of the captured tissue debris intothe catheter.

FIGS. 69I to 69K illustrate one method for adhering the tissue to beablated via a suction force applied to the underlying tissue to beablated.

DETAILED DESCRIPTION OF THE INVENTION

A tissue-imaging and manipulation apparatus described below is able toprovide real-time images in vivo of tissue regions within a body lumensuch as a heart, which is filled with blood flowing dynamicallytherethrough and is also able to provide intravascular tools andinstruments for performing various procedures upon the imaged tissueregions. Such an apparatus may be utilized for many procedures, e.g.,facilitating transseptal access to the left atrium, cannulating thecoronary sinus, diagnosis of valve regurgitation/stenosis,valvuloplasty, atrial appendage closure, arrhythmogenic focus ablation,among other procedures.

One variation of a tissue access and imaging apparatus is shown in thedetail perspective views of FIGS. 1A to 1C. As shown in FIG. 1A, tissueimaging and manipulation assembly 10 may be delivered intravascularlythrough the patient's body in a low-profile configuration via a deliverycatheter or sheath 14. In the case of treating tissue, such as themitral valve located at the outflow tract of the left atrium of theheart, it is generally desirable to enter or access the left atriumwhile minimizing trauma to the patient. To non-operatively effect suchaccess, one conventional approach involves puncturing the intra-atrialseptum from the right atrial chamber to the left atrial chamber in aprocedure commonly called a transseptal procedure or septostomy. Forprocedures such as percutaneous valve repair and replacement,transseptal access to the left atrial chamber of the heart may allow forlarger devices to be introduced into the venous system than cangenerally be introduced percutaneously into the arterial system.

When the imaging and manipulation assembly 10 is ready to be utilizedfor imaging tissue, imaging hood 12 may be advanced relative to catheter14 and deployed from a distal opening of catheter 14, as shown by thearrow. Upon deployment, imaging hood 12 may be unconstrained to expandor open into a deployed imaging configuration, as shown in FIG. 1B.Imaging hood 12 may be fabricated from a variety of pliable orconformable biocompatible material including but not limited to, e.g.,polymeric, plastic, or woven materials. One example of a woven materialis Kevlar® (E.I. du Pont de Nemours, Wilmington, Del.), which is anaramid and which can be made into thin, e.g., less than 0.001 in.,materials which maintain enough integrity for such applicationsdescribed herein. Moreover, the imaging hood 12 may be fabricated from atranslucent or opaque material and in a variety of different colors tooptimize or attenuate any reflected lighting from surrounding fluids orstructures, i.e., anatomical or mechanical structures or instruments. Ineither case, imaging hood 12 may be fabricated into a uniform structureor a scaffold-supported structure, in which case a scaffold made of ashape memory alloy, such as Nitinol, or a spring steel, or plastic,etc., may be fabricated and covered with the polymeric, plastic, orwoven material. Hence, imaging hood 12 may comprise any of a widevariety of barriers or membrane structures, as may generally be used tolocalize displacement of blood or the like from a selected volume of abody lumen or heart chamber. In exemplary embodiments, a volume withinan inner surface 13 of imaging hood 12 will be significantly less than avolume of the hood 12 between inner surface 13 and outer surface 11.

Imaging hood 12 may be attached at interface 24 to a deployment catheter16 which may be translated independently of deployment catheter orsheath 14. Attachment of interface 24 may be accomplished through anynumber of conventional methods. Deployment catheter 16 may define afluid delivery lumen 18 as well as an imaging lumen 20 within which anoptical imaging fiber or assembly may be disposed for imaging tissue.When deployed, imaging hood 12 may expand into any number of shapes,e.g., cylindrical, conical as shown, semi-spherical, etc., provided thatan open area or field 26 is defined by imaging hood 12. The open area 26is the area within which the tissue region of interest may be imaged.Imaging hood 12 may also define an atraumatic contact lip or edge 22 forplacement or abutment against the tissue region of interest. Moreover,the diameter of imaging hood 12 at its maximum fully deployed diameter,e.g., at contact lip or edge 22, is typically greater relative to adiameter of the deployment catheter 16 (although a diameter of contactlip or edge 22 may be made to have a smaller or equal diameter ofdeployment catheter 16). For instance, the contact edge diameter mayrange anywhere from 1 to 5 times (or even greater, as practicable) adiameter of deployment catheter 16. FIG. 1C shows an end view of theimaging hood 12 in its deployed configuration. Also shown are thecontact lip or edge 22 and fluid delivery lumen 18 and imaging lumen 20.

The imaging and manipulation assembly 10 may additionally define aguidewire lumen therethrough, e.g., a concentric or eccentric lumen, asshown in the side and end views, respectively, of FIGS. 1D to 1F. Thedeployment catheter 16 may define guidewire lumen 19 for facilitatingthe passage of the system over or along a guidewire 17, which may beadvanced intravascularly within a body lumen. The deployment catheter 16may then be advanced over the guidewire 17, as generally known in theart.

In operation, after imaging hood 12 has been deployed, as in FIG. 1B,and desirably positioned against the tissue region to be imaged alongcontact edge 22, the displacing fluid may be pumped at positive pressurethrough fluid delivery lumen 18 until the fluid fills open area 26completely and displaces any fluid 28 from within open area 26. Thedisplacing fluid flow may be laminarized to improve its clearing effectand to help prevent blood from re-entering the imaging hood 12.Alternatively, fluid flow may be started before the deployment takesplace. The displacing fluid, also described herein as imaging fluid, maycomprise any biocompatible fluid, e.g., saline, water, plasma, etc.,which is sufficiently transparent to allow for relatively undistortedvisualization through the fluid. Alternatively or additionally, anynumber of therapeutic drugs may be suspended within the fluid or maycomprise the fluid itself which is pumped into open area 26 and which issubsequently passed into and through the heart and the patient body.

As seen in the example of FIGS. 2A and 2B, deployment catheter 16 may bemanipulated to position deployed imaging hood 12 against or near theunderlying tissue region of interest to be imaged, in this example aportion of annulus A of mitral valve MV within the left atrial chamber.As the surrounding blood 30 flows around imaging hood 12 and within openarea 26 defined within imaging hood 12, as seen in FIG. 2A, theunderlying annulus A is obstructed by the opaque blood 30 and isdifficult to view through the imaging lumen 20. The translucent fluid28, such as saline, may then be pumped through fluid delivery lumen 18,intermittently or continuously, until the blood 30 is at leastpartially, and preferably completely, displaced from within open area 26by fluid 28, as shown in FIG. 2B.

Although contact edge 22 need not directly contact the underlyingtissue, it is at least preferably brought into close proximity to thetissue such that the flow of clear fluid 28 from open area 26 may bemaintained to inhibit significant backflow of blood 30 back into openarea 26. Contact edge 22 may also be made of a soft elastomeric materialsuch as certain soft grades of silicone or polyurethane, as typicallyknown, to help contact edge 22 conform to an uneven or rough underlyinganatomical tissue surface. Once the blood 30 has been displaced fromimaging hood 12, an image may then be viewed of the underlying tissuethrough the clear fluid 30. This image may then be recorded or availablefor real-time viewing for performing a therapeutic procedure. Thepositive flow of fluid 28 may be maintained continuously to provide forclear viewing of the underlying tissue. Alternatively, the fluid 28 maybe pumped temporarily or sporadically only until a clear view of thetissue is available to be imaged and recorded, at which point the fluidflow 28 may cease and blood 30 may be allowed to seep or flow back intoimaging hood 12. This process may be repeated a number of times at thesame tissue region or at multiple tissue regions.

In desirably positioning the assembly at various regions within thepatient body, a number of articulation and manipulation controls may beutilized. For example, as shown in the articulatable imaging assembly 40in FIG. 3A, one or more push-pull wires 42 may be routed throughdeployment catheter 16 for steering the distal end portion of the devicein various directions 46 to desirably position the imaging hood 12adjacent to a region of tissue to be visualized. Depending upon thepositioning and the number of push-pull wires 42 utilized, deploymentcatheter 16 and imaging hood 12 may be articulated into any number ofconfigurations 44. The push-pull wire or wires 42 may be articulated viatheir proximal ends from outside the patient body manually utilizing oneor more controls. Alternatively, deployment catheter 16 may bearticulated by computer control, as further described below.

Additionally or alternatively, an articulatable delivery catheter 48,which may be articulated via one or more push-pull wires and having animaging lumen and one or more working lumens, may be delivered throughthe deployment catheter 16 and into imaging hood 12. With a distalportion of articulatable delivery catheter 48 within imaging hood 12,the clear displacing fluid may be pumped through delivery catheter 48 ordeployment catheter 16 to clear the field within imaging hood 12. Asshown in FIG. 3B, the articulatable delivery catheter 48 may bearticulated within the imaging hood to obtain a better image of tissueadjacent to the imaging hood 12. Moreover, articulatable deliverycatheter 48 may be articulated to direct an instrument or tool passedthrough the catheter 48, as described in detail below, to specific areasof tissue imaged through imaging hood 12 without having to repositiondeployment catheter 16 and re-clear the imaging field within hood 12.

Alternatively, rather than passing an articulatable delivery catheter 48through the deployment catheter 16, a distal portion of the deploymentcatheter 16 itself may comprise a distal end 49 which is articulatablewithin imaging hood 12, as shown in FIG. 3C. Directed imaging,instrument delivery, etc., may be accomplished directly through one ormore lumens within deployment catheter 16 to specific regions of theunderlying tissue imaged within imaging hood 12.

Visualization within the imaging hood 12 may be accomplished through animaging lumen 20 defined through deployment catheter 16, as describedabove. In such a configuration, visualization is available in astraight-line manner, i.e., images are generated from the field distallyalong a longitudinal axis defined by the deployment catheter 16.Alternatively or additionally, an articulatable imaging assembly havinga pivotable support member 50 may be connected to, mounted to, orotherwise passed through deployment catheter 16 to provide forvisualization off-axis relative to the longitudinal axis defined bydeployment catheter 16, as shown in FIG. 4A. Support member 50 may havean imaging element 52, e.g., a CCD or CMOS imager or optical fiber,attached at its distal end with its proximal end connected to deploymentcatheter 16 via a pivoting connection 54.

If one or more optical fibers are utilized for imaging, the opticalfibers 58 may be passed through deployment catheter 16, as shown in thecross-section of FIG. 4B, and routed through the support member 50. Theuse of optical fibers 58 may provide for increased diameter sizes of theone or several lumens 56 through deployment catheter 16 for the passageof diagnostic and/or therapeutic tools therethrough. Alternatively,electronic chips, such as a charge coupled device (CCD) or a CMOSimager, which are typically known, may be utilized in place of theoptical fibers 58, in which case the electronic imager may be positionedin the distal portion of the deployment catheter 16 with electric wiresbeing routed proximally through the deployment catheter 16.Alternatively, the electronic imagers may be wirelessly coupled to areceiver for the wireless transmission of images. Additional opticalfibers or light emitting diodes (LEDs) can be used to provide lightingfor the image or operative theater, as described below in furtherdetail. Support member 50 may be pivoted via connection 54 such that themember 50 can be positioned in a low-profile configuration withinchannel or groove 60 defined in a distal portion of catheter 16, asshown in the cross-section of FIG. 4C. During intravascular delivery ofdeployment catheter 16 through the patient body, support member 50 canbe positioned within channel or groove 60 with imaging hood 12 also inits low-profile configuration. During visualization, imaging hood 12 maybe expanded into its deployed configuration and support member 50 may bedeployed into its off-axis configuration for imaging the tissue adjacentto hood 12, as in FIG. 4A. Other configurations for support member 50for off-axis visualization may be utilized, as desired.

FIG. 5 shows an illustrative cross-sectional view of a heart H havingtissue regions of interest being viewed via an imaging assembly 10. Inthis example, delivery catheter assembly 70 may be introducedpercutaneously into the patient's vasculature and advanced through thesuperior vena cava SVC and into the right atrium RA. The deliverycatheter or sheath 72 may be articulated through the atrial septum ASand into the left atrium LA for viewing or treating the tissue, e.g.,the annulus A, surrounding the mitral valve MV. As shown, deploymentcatheter 16 and imaging hood 12 may be advanced out of delivery catheter72 and brought into contact or in proximity to the tissue region ofinterest. In other examples, delivery catheter assembly 70 may beadvanced through the inferior vena cava IVC, if so desired. Moreover,other regions of the heart H, e.g., the right ventricle RV or leftventricle LV, may also be accessed and imaged or treated by imagingassembly 10.

In accessing regions of the heart H or other parts of the body, thedelivery catheter or sheath 14 may comprise a conventionalintra-vascular catheter or an endoluminal delivery device.Alternatively, robotically-controlled delivery catheters may also beoptionally utilized with the imaging assembly described herein, in whichcase a computer-controller 74 may be used to control the articulationand positioning of the delivery catheter 14. An example of arobotically-controlled delivery catheter which may be utilized isdescribed in further detail in US Pat. Pub. 2002/0087169 A1 to Brock etal. entitled “Flexible Instrument”, which is incorporated herein byreference in its entirety. Other robotically-controlled deliverycatheters manufactured by Hansen Medical, Inc. (Mountain View, Calif.)may also be utilized with the delivery catheter 14.

To facilitate stabilization of the deployment catheter 16 during aprocedure, one or more inflatable balloons or anchors 76 may bepositioned along the length of catheter 16, as shown in FIG. 6A. Forexample, when utilizing a transseptal approach across the atrial septumAS into the left atrium LA, the inflatable balloons 76 may be inflatedfrom a low-profile into their expanded configuration to temporarilyanchor or stabilize the catheter 16 position relative to the heart H.FIG. 6B shows a first balloon 78 inflated while FIG. 6C also shows asecond balloon 80 inflated proximal to the first balloon 78. In such aconfiguration, the septal wall AS may be wedged or sandwiched betweenthe balloons 78, 80 to temporarily stabilize the catheter 16 and imaginghood 12. A single balloon 78 or both balloons 78, 80 may be used. Otheralternatives may utilize expandable mesh members, malecots, or any othertemporary expandable structure. After a procedure has been accomplished,the balloon assembly 76 may be deflated or re-configured into alow-profile for removal of the deployment catheter 16.

To further stabilize a position of the imaging hood 12 relative to atissue surface to be imaged, various anchoring mechanisms may beoptionally employed for temporarily holding the imaging hood 12 againstthe tissue. Such anchoring mechanisms may be particularly useful forimaging tissue which is subject to movement, e.g., when imaging tissuewithin the chambers of a beating heart. A tool delivery catheter 82having at least one instrument lumen and an optional visualization lumenmay be delivered through deployment catheter 16 and into an expandedimaging hood 12. As the imaging hood 12 is brought into contact againsta tissue surface T to be examined, anchoring mechanisms such as ahelical tissue piercing device 84 may be passed through the tooldelivery catheter 82, as shown in FIG. 7A, and into imaging hood 12.

The helical tissue engaging device 84 may be torqued from its proximalend outside the patient body to temporarily anchor itself into theunderlying tissue surface T. Once embedded within the tissue T, thehelical tissue engaging device 84 may be pulled proximally relative todeployment catheter 16 while the deployment catheter 16 and imaging hood12 are pushed distally, as indicated by the arrows in FIG. 7B, to gentlyforce the contact edge or lip 22 of imaging hood against the tissue T.The positioning of the tissue engaging device 84 may be lockedtemporarily relative to the deployment catheter 16 to ensure securepositioning of the imaging hood 12 during a diagnostic or therapeuticprocedure within the imaging hood 12. After a procedure, tissue engagingdevice 84 may be disengaged from the tissue by torquing its proximal endin the opposite direction to remove the anchor form the tissue T and thedeployment catheter 16 may be repositioned to another region of tissuewhere the anchoring process may be repeated or removed from the patientbody. The tissue engaging device 84 may also be constructed from otherknown tissue engaging devices such as vacuum-assisted engagement orgrasper-assisted engagement tools, among others.

Although a helical anchor 84 is shown, this is intended to beillustrative and other types of temporary anchors may be utilized, e.g.,hooked or barbed anchors, graspers, etc. Moreover, the tool deliverycatheter 82 may be omitted entirely and the anchoring device may bedelivered directly through a lumen defined through the deploymentcatheter 16.

In another variation where the tool delivery catheter 82 may be omittedentirely to temporarily anchor imaging hood 12, FIG. 7C shows an imaginghood 12 having one or more tubular support members 86, e.g., foursupport members 86 as shown, integrated with the imaging hood 12. Thetubular support members 86 may define lumens therethrough each havinghelical tissue engaging devices 88 positioned within. When an expandedimaging hood 12 is to be temporarily anchored to the tissue, the helicaltissue engaging devices 88 may be urged distally to extend from imaginghood 12 and each may be torqued from its proximal end to engage theunderlying tissue T. Each of the helical tissue engaging devices 88 maybe advanced through the length of deployment catheter 16 or they may bepositioned within tubular support members 86 during the delivery anddeployment of imaging hood 12. Once the procedure within imaging hood 12is finished, each of the tissue engaging devices 88 may be disengagedfrom the tissue and the imaging hood 12 may be repositioned to anotherregion of tissue or removed from the patient body.

An illustrative example is shown in FIG. 8A of a tissue imaging assemblyconnected to a fluid delivery system 90 and to an optional processor 98and image recorder and/or viewer 100. The fluid delivery system 90 maygenerally comprise a pump 92 and an optional valve 94 for controllingthe flow rate of the fluid into the system. A fluid reservoir 96,fluidly connected to pump 92, may hold the fluid to be pumped throughimaging hood 12. An optional central processing unit or processor 98 maybe in electrical communication with fluid delivery system 90 forcontrolling flow parameters such as the flow rate and/or velocity of thepumped fluid. The processor 98 may also be in electrical communicationwith an image recorder and/or viewer 100 for directly viewing the imagesof tissue received from within imaging hood 12. Imager recorder and/orviewer 100 may also be used not only to record the image but also thelocation of the viewed tissue region, if so desired.

Optionally, processor 98 may also be utilized to coordinate the fluidflow and the image capture. For instance, processor 98 may be programmedto provide for fluid flow from reservoir 96 until the tissue area hasbeen displaced of blood to obtain a clear image. Once the image has beendetermined to be sufficiently clear, either visually by a practitioneror by computer, an image of the tissue may be captured automatically byrecorder 100 and pump 92 may be automatically stopped or slowed byprocessor 98 to cease the fluid flow into the patient. Other variationsfor fluid delivery and image capture are, of course, possible and theaforementioned configuration is intended only to be illustrative and notlimiting.

FIG. 8B shows a further illustration of a hand-held variation of thefluid delivery and tissue manipulation system 110. In this variation,system 110 may have a housing or handle assembly 112 which can be heldor manipulated by the physician from outside the patient body. The fluidreservoir 114, shown in this variation as a syringe, can be fluidlycoupled to the handle assembly 112 and actuated via a pumping mechanism116, e.g., lead screw. Fluid reservoir 114 may be a simple reservoirseparated from the handle assembly 112 and fluidly coupled to handleassembly 112 via one or more tubes. The fluid flow rate and othermechanisms may be metered by the electronic controller 118.

Deployment of imaging hood 12 maybe actuated by a hood deployment switch120 located on the handle assembly 112 while dispensation of the fluidfrom reservoir 114 may be actuated by a fluid deployment switch 122,which can be electrically coupled to the controller 118. Controller 118may also be electrically coupled to a wired or wireless antenna 124optionally integrated with the handle assembly 112, as shown in thefigure. The wireless antenna 124 can be used to wirelessly transmitimages captured from the imaging hood 12 to a receiver, e.g., viaBluetooth® wireless technology (Bluetooth SIG, Inc., Bellevue, Wash.),RF, etc., for viewing on a monitor 128 or for recording for laterviewing.

Articulation control of the deployment catheter 16, or a deliverycatheter or sheath 14 through which the deployment catheter 16 may bedelivered, may be accomplished by computer control, as described above,in which case an additional controller may be utilized with handleassembly 112. In the case of manual articulation, handle assembly 112may incorporate one or more articulation controls 126 for manualmanipulation of the position of deployment catheter 16. Handle assembly112 may also define one or more instrument ports 130 through which anumber of intravascular tools may be passed for tissue manipulation andtreatment within imaging hood 12, as described further below.Furthermore, in certain procedures, fluid or debris may be sucked intoimaging hood 12 for evacuation from the patient body by optionallyfluidly coupling a suction pump 132 to handle assembly 112 or directlyto deployment catheter 16.

As described above, fluid may be pumped continuously into imaging hood12 to provide for clear viewing of the underlying tissue. Alternatively,fluid may be pumped temporarily or sporadically only until a clear viewof the tissue is available to be imaged and recorded, at which point thefluid flow may cease and the blood may be allowed to seep or flow backinto imaging hood 12. FIGS. 9A to 9C illustrate an example of capturingseveral images of the tissue at multiple regions. Deployment catheter 16may be desirably positioned and imaging hood 12 deployed and broughtinto position against a region of tissue to be imaged, in this examplethe tissue surrounding a mitral valve MV within the left atrium of apatient's heart. The imaging hood 12 may be optionally anchored to thetissue, as described above, and then cleared by pumping the imagingfluid into the hood 12. Once sufficiently clear, the tissue may bevisualized and the image captured by control electronics 118. The firstcaptured image 140 may be stored and/or transmitted wirelessly 124 to amonitor 128 for viewing by the physician, as shown in FIG. 9A.

The deployment catheter 16 may be then repositioned to an adjacentportion of mitral valve MV, as shown in FIG. 9B, where the process maybe repeated to capture a second image 142 for viewing and/or recording.The deployment catheter 16 may again be repositioned to another regionof tissue, as shown in FIG. 9C, where a third image 144 may be capturedfor viewing and/or recording. This procedure may be repeated as manytimes as necessary for capturing a comprehensive image of the tissuesurrounding mitral valve MV, or any other tissue region. When thedeployment catheter 16 and imaging hood 12 is repositioned from tissueregion to tissue region, the pump may be stopped during positioning andblood or surrounding fluid may be allowed to enter within imaging hood12 until the tissue is to be imaged, where the imaging hood 12 may becleared, as above.

As mentioned above, when the imaging hood 12 is cleared by pumping theimaging fluid within for clearing the blood or other bodily fluid, thefluid may be pumped continuously to maintain the imaging fluid withinthe hood 12 at a positive pressure or it may be pumped under computercontrol for slowing or stopping the fluid flow into the hood 12 upondetection of various parameters or until a clear image of the underlyingtissue is obtained. The control electronics 118 may also be programmedto coordinate the fluid flow into the imaging hood 12 with variousphysical parameters to maintain a clear image within imaging hood 12.

One example is shown in FIG. 10A which shows a chart 150 illustratinghow fluid pressure within the imaging hood 12 may be coordinated withthe surrounding blood pressure. Chart 150 shows the cyclical bloodpressure 156 alternating between diastolic pressure 152 and systolicpressure 154 over time T due to the beating motion of the patient heart.The fluid pressure of the imaging fluid, indicated by plot 160, withinimaging hood 12 may be automatically timed to correspond to the bloodpressure changes 160 such that an increased pressure is maintainedwithin imaging hood 12 which is consistently above the blood pressure156 by a slight increase ΔP, as illustrated by the pressure differenceat the peak systolic pressure 158. This pressure difference, ΔP, may bemaintained within imaging hood 12 over the pressure variance of thesurrounding blood pressure to maintain a positive imaging fluid pressurewithin imaging hood 12 to maintain a clear view of the underlyingtissue. One benefit of maintaining a constant ΔP is a constant flow andmaintenance of a clear field.

FIG. 10B shows a chart 162 illustrating another variation formaintaining a clear view of the underlying tissue where one or moresensors within the imaging hood 12, as described in further detailbelow, may be configured to sense pressure changes within the imaginghood 12 and to correspondingly increase the imaging fluid pressurewithin imaging hood 12. This may result in a time delay, ΔT, asillustrated by the shifted fluid pressure 160 relative to the cyclingblood pressure 156, although the time delays ΔT may be negligible inmaintaining the clear image of the underlying tissue. Predictivesoftware algorithms can also be used to substantially eliminate thistime delay by predicting when the next pressure wave peak will arriveand by increasing the pressure ahead of the pressure wave's arrival byan amount of time equal to the aforementioned time delay to essentiallycancel the time delay out.

The variations in fluid pressure within imaging hood 12 may beaccomplished in part due to the nature of imaging hood 12. An inflatableballoon, which is conventionally utilized for imaging tissue, may beaffected by the surrounding blood pressure changes. On the other hand,an imaging hood 12 retains a constant volume therewithin and isstructurally unaffected by the surrounding blood pressure changes, thusallowing for pressure increases therewithin. The material that hood 12is made from may also contribute to the manner in which the pressure ismodulated within this hood 12. A stiffer hood material, such as highdurometer polyurethane or Nylon, may facilitate the maintaining of anopen hood when deployed. On the other hand, a relatively lower durometeror softer material, such as a low durometer PVC or polyurethane, maycollapse from the surrounding fluid pressure and may not adequatelymaintain a deployed or expanded hood.

Turning now to the imaging hood, other variations of the tissue imagingassembly may be utilized, as shown in FIG. 11A, which shows anothervariation comprising an additional imaging balloon 172 within an imaginghood 174. In this variation, an expandable balloon 172 having atranslucent skin may be positioned within imaging hood 174. Balloon 172may be made from any distensible biocompatible material havingsufficient translucent properties which allow for visualizationtherethrough. Once the imaging hood 174 has been deployed against thetissue region of interest, balloon 172 may be filled with a fluid, suchas saline, or less preferably a gas, until balloon 172 has been expandeduntil the blood has been sufficiently displaced. The balloon 172 maythus be expanded proximal to or into contact against the tissue regionto be viewed. The balloon 172 can also be filled with contrast media toallow it to be viewed on fluoroscopy to aid in its positioning. Theimager, e.g., fiber optic, positioned within deployment catheter 170 maythen be utilized to view the tissue region through the balloon 172 andany additional fluid which may be pumped into imaging hood 174 via oneor more optional fluid ports 176, which may be positioned proximally ofballoon 172 along a portion of deployment catheter 170. Alternatively,balloon 172 may define one or more holes over its surface which allowfor seepage or passage of the fluid contained therein to escape anddisplace the blood from within imaging hood 174.

FIG. 11B shows another alternative in which balloon 180 may be utilizedalone. Balloon 180, attached to deployment catheter 178, may be filledwith fluid, such as saline or contrast media, and is preferably allowedto come into direct contact with the tissue region to be imaged.

FIG. 12A shows another alternative in which deployment catheter 16incorporates imaging hood 12, as above, and includes an additionalflexible membrane 182 within imaging hood 12. Flexible membrane 182 maybe attached at a distal end of catheter 16 and optionally at contactedge 22. Imaging hood 12 may be utilized, as above, and membrane 182 maybe deployed from catheter 16 in vivo or prior to placing catheter 16within a patient to reduce the volume within imaging hood 12. The volumemay be reduced or minimized to reduce the amount of fluid dispensed forvisualization or simply reduced depending upon the area of tissue to bevisualized.

FIGS. 12B and 12C show yet another alternative in which imaging hood 186may be withdrawn proximally within deployment catheter 184 or deployeddistally from catheter 186, as shown, to vary the volume of imaging hood186 and thus the volume of dispensed fluid. Imaging hood 186 may be seenin FIG. 12B as being partially deployed from, e.g., a circumferentiallydefined lumen within catheter 184, such as annular lumen 188. Theunderlying tissue may be visualized with imaging hood 186 only partiallydeployed. Alternatively, imaging hood 186′ may be fully deployed, asshown in FIG. 12C, by urging hood 186′ distally out from annular lumen188. In this expanded configuration, the area of tissue to be visualizedmay be increased as hood 186′ is expanded circumferentially.

FIGS. 13A and 13B show perspective and cross-sectional side views,respectively, of yet another variation of imaging assembly which mayutilize a fluid suction system for minimizing the amount of fluidinjected into the patient's heart or other body lumen during tissuevisualization. Deployment catheter 190 in this variation may define aninner tubular member 196 which may be integrated with deploymentcatheter 190 or independently translatable. Fluid delivery lumen 198defined through member 196 may be fluidly connected to imaging hood 192,which may also define one or more open channels 194 over its contact lipregion. Fluid pumped through fluid delivery lumen 198 may thus fill openarea 202 to displace any blood or other fluids or objects therewithin.As the clear fluid is forced out of open area 202, it may be sucked ordrawn immediately through one or more channels 194 and back intodeployment catheter 190. Tubular member 196 may also define one or moreadditional working channels 200 for the passage of any tools orvisualization devices.

In deploying the imaging hood in the examples described herein, theimaging hood may take on any number of configurations when positioned orconfigured for a low-profile delivery within the delivery catheter, asshown in the examples of FIGS. 14A to 14D. These examples are intendedto be illustrative and are not intended to be limiting in scope. FIG.14A shows one example in which imaging hood 212 maybe compressed withincatheter 210 by folding hood 212 along a plurality of pleats. Hood 212may also comprise scaffolding or frame 214 made of a super-elastic orshape memory material or alloy, e.g., Nitinol, Elgiloy, shape memorypolymers, electroactive polymers, or a spring stainless steel. The shapememory material may act to expand or deploy imaging hood 212 into itsexpanded configuration when urged in the direction of the arrow from theconstraints of catheter 210.

FIG. 14B shows another example in which imaging hood, 216 may beexpanded or deployed from catheter 210 from a folded and overlappingconfiguration. Frame or scaffolding 214 may also be utilized in thisexample. FIG. 14C shows yet another example in which imaging hood 218may be rolled, inverted, or everted upon itself for deployment. In yetanother example, FIG. 14D shows a configuration in which imaging hood220 may be fabricated from an extremely compliant material which allowsfor hood 220 to be simply compressed into a low-profile shape. From thislow-profile compressed shape, simply releasing hood 220 may allow for itto expand into its deployed configuration, especially if a scaffold orframe of a shape memory or superelastic material, e.g., Nitinol, isutilized in its construction.

Another variation for expanding the imaging hood is shown in FIGS. 15Aand 15B which illustrates an helically expanding frame or support 230.In its constrained low-profile configuration, shown in FIG. 15A, helicalframe 230 may be integrated with the imaging hood 12 membrane. When freeto expand, as shown in FIG. 15B, helical frame 230 may expand into aconical or tapered shape. Helical frame 230 may alternatively be madeout of heat-activated Nitinol to allow it to expand upon application ofa current.

FIGS. 16A and 16B show yet another variation in which imaging hood 12may comprise one or more hood support members 232 integrated with thehood membrane. These longitudinally attached support members 232 may bepivotably attached at their proximal ends to deployment catheter 16. Oneor more pullwires 234 may be routed through the length of deploymentcatheter 16 and extend through one or more openings 238 defined indeployment catheter 16 proximally to imaging hood 12 into attachmentwith a corresponding support member 232 at a pullwire attachment point236. The support members 232 may be fabricated from a plastic or metal,such as stainless steel. Alternatively, the support members 232 may bemade from a superelastic or shape memory alloy, such as Nitinol, whichmay self-expand into its deployed configuration without the use or needof pullwires. A heat-activated Nitinol may also be used which expandsupon the application of thermal energy or electrical energy. In anotheralternative, support members 232 may also be constructed as inflatablelumens utilizing, e.g., PET balloons. From its low-profile deliveryconfiguration shown in FIG. 16A, the one or more pullwires 234 may betensioned from their proximal ends outside the patient body to pull acorresponding support member 232 into a deployed configuration, as shownin FIG. 16B, to expand imaging hood 12. To reconfigure imaging hood 12back into its low profile, deployment catheter 16 may be pulledproximally into a constraining catheter or the pullwires 234 may besimply pushed distally to collapse imaging hood 12.

FIGS. 17A and 17B show yet another variation of imaging hood 240 havingat least two or more longitudinally positioned support members 242supporting the imaging hood membrane. The support members 242 each havecross-support members 244 which extend diagonally between and arepivotably attached to the support members 242. Each of the cross-supportmembers 244 may be pivotably attached to one another where theyintersect between the support members 242. A jack or screw member 246maybe coupled to each cross-support member 244 at this intersectionpoint and a torquing member, such as a torqueable wire 248, may becoupled to each jack or screw member 246 and extend proximally throughdeployment catheter 16 to outside the patient body. From outside thepatient body, the torqueable wires 248 may be torqued to turn the jackor screw member 246 which in turn urges the cross-support members 244 toangle relative to one another and thereby urge the support members 242away from one another. Thus, the imaging hood 240 may be transitionedfrom its low-profile, shown in FIG. 17A, to its expanded profile, shownin FIG. 17B, and back into its low-profile by torquing wires 248.

FIGS. 18A and 18B show yet another variation on the imaging hood and itsdeployment. As shown, a distal portion of deployment catheter 16 mayhave several pivoting members 250, e.g., two to four sections, whichform a tubular shape in its low profile configuration, as shown in FIG.18A. When pivoted radially about deployment catheter 16, pivotingmembers 250 may open into a deployed configuration having distensible orexpanding membranes 252 extending over the gaps in-between the pivotingmembers 250, as shown in FIG. 18B. The distensible membrane 252 may beattached to the pivoting members 250 through various methods, e.g.,adhesives, such that when the pivoting members 250 are fully extendedinto a conical shape, the pivoting members 250 and membrane 252 form aconical shape for use as an imaging hood. The distensible membrane 252may be made out of a porous material such as a mesh or PTFE or out of atranslucent or transparent polymer such as polyurethane, PVC, Nylon,etc.

FIGS. 19A and 19B show yet another variation where the distal portion ofdeployment catheter 16 may be fabricated from a flexible metallic orpolymeric material to form a radially expanding hood 254. A plurality ofslots 256 may be formed in a uniform pattern over the distal portion ofdeployment catheter 16, as shown in FIG. 19A. The slots 256 may beformed in a pattern such that when the distal portion is urged radiallyopen, utilizing any of the methods described above, a radially expandedand conically-shaped hood 254 may be formed by each of the slots 256expanding into an opening, as shown in FIG. 19B. A distensible membrane258 may overlie the exterior surface or the interior surface of the hood254 to form a fluid-impermeable hood 254 such that the hood 254 may beutilized as an imaging hood. Alternatively, the distensible membrane 258may alternatively be formed in each opening 258 to form thefluid-impermeable hood 254. Once the imaging procedure has beencompleted, hood 254 may be retracted into its low-profile configuration.

Yet another configuration for the imaging hood may be seen in FIGS. 20Aand 20B where the imaging hood may be formed from a plurality ofoverlapping hood members 260 which overlie one another in an overlappingpattern. When expanded, each of the hood members 260 may extend radiallyoutward relative to deployment catheter 16 to form a conically-shapedimaging hood, as shown in FIG. 20B. Adjacent hood members 260 mayoverlap one another along an overlapping interface 262 to form afluid-retaining surface within the imaging hood. Moreover, the hoodmembers 260 may be made from any number of biocompatible materials,e.g., Nitinol, stainless steel, polymers, etc., which are sufficientlystrong to optionally retract surrounding tissue from the tissue regionof interest.

Although it is generally desirable to have an imaging hood contactagainst a tissue surface in a normal orientation, the imaging hood maybe alternatively configured to contact the tissue surface at an acuteangle. An imaging hood configured for such contact against tissue mayalso be especially suitable for contact against tissue surfaces havingan unpredictable or uneven anatomical geography. For instance, as shownin the variation of FIG. 21A, deployment catheter 270 may have animaging hood 272 that is configured to be especially compliant. In thisvariation, imaging hood 272 may be comprised of one or more sections 274that are configured to fold or collapse, e.g., by utilizing a pleatedsurface. Thus, as shown in FIG. 21B, when imaging hood 272 is contactedagainst uneven tissue surface T, sections 274 are able to conformclosely against the tissue. These sections 274 may be individuallycollapsible by utilizing an accordion style construction to allowconformation, e.g., to the trabeculae in the heart or the uneven anatomythat may be found inside the various body lumens.

In yet another alternative, FIG. 22A shows another variation in which animaging hood 282 is attached to deployment catheter 280. The contact lipor edge 284 may comprise one or more electrical contacts 286 positionedcircumferentially around contact edge 284. The electrical contacts 286may be configured to contact the tissue and indicate affirmativelywhether tissue contact was achieved, e.g., by measuring the differentialimpedance between blood and tissue. Alternatively, a processor, e.g.,processor 98, in electrical communication with contacts 286 may beconfigured to determine what type of tissue is in contact withelectrical contacts 286. In yet another alternative, the processor 98may be configured to measure any electrical activity that may beoccurring in the underlying tissue, e.g., accessory pathways, for thepurposes of electrically mapping the cardiac tissue and subsequentlytreating, as described below, any arrhythmias which may be detected.

Another variation for ensuring contact between imaging hood 282 and theunderlying tissue may be seen in FIG. 22B. This variation may have aninflatable contact edge 288 around the circumference of imaging hood282. The inflatable contact edge 288 may be inflated with a fluid or gasthrough inflation lumen 289 when the imaging hood 282 is to be placedagainst a tissue surface having an uneven or varied anatomy. Theinflated circumferential surface 288 may provide for continuous contactover the hood edge by conforming against the tissue surface andfacilitating imaging fluid retention within hood 282.

Aside from the imaging hood, various instrumentation may be utilizedwith the imaging and manipulation system. For instance, after the fieldwithin imaging hood 12 has been cleared of the opaque blood and theunderlying tissue is visualized through the clear fluid, blood may seepback into the imaging hood 12 and obstruct the view. One method forautomatically maintaining a clear imaging field may utilize atransducer, e.g., an ultrasonic transducer 290, positioned at the distalend of deployment catheter within the imaging hood 12, as shown in FIG.23. The transducer 290 may send an energy pulse 292 into the imaginghood 12 and wait to detect back-scattered energy 294 reflected fromdebris or blood within the imaging hood 12. If back-scattered energy isdetected, the pump may be actuated automatically to dispense more fluidinto the imaging hood until the debris or blood is no longer detected.

Alternatively, one or more sensors 300 may be positioned on the imaginghood 12 itself, as shown in FIG. 24A, to detect a number of differentparameters. For example, sensors 300 may be configured to detect for thepresence of oxygen in the surrounding blood, blood and/or imaging fluidpressure, color of the fluid within the imaging hood, etc. Fluid colormay be particularly useful in detecting the presence of blood within theimaging hood 12 by utilizing a reflective type sensor to detect backreflection from blood. Any reflected light from blood which may bepresent within imaging hood 12 may be optically or electricallytransmitted through deployment catheter 16 and to a red colored filterwithin control electronics 118. Any red color which may be detected mayindicate the presence of blood and trigger a signal to the physician orautomatically actuate the pump to dispense more fluid into the imaginghood 12 to clear the blood.

Alternative methods for detecting the presence of blood within the hood12 may include detecting transmitted light through the imaging fluidwithin imaging hood 12. If a source of white light, e.g., utilizing LEDsor optical fibers, is illuminated inside imaging hood 12, the presenceof blood may cause the color red to be filtered through this fluid. Thedegree or intensity of the red color detected may correspond to theamount of blood present within imaging hood 12. A red color sensor cansimply comprise, in one variation, a phototransistor with a redtransmitting filter over it which can establish how much red light isdetected, which in turn can indicate the presence of blood withinimaging hood 12. Once blood is detected, the system may pump moreclearing fluid through and enable closed loop feedback control of theclearing fluid pressure and flow level.

Any number of sensors may be positioned along the exterior 302 ofimaging hood 12 or within the interior 304 of imaging hood 12 to detectparameters not only exteriorly to imaging hood 12 but also withinimaging hood 12. Such a configuration, as shown in FIG. 24B, may beparticularly useful for automatically maintaining a clear imaging fieldbased upon physical parameters such as blood pressure, as describedabove for FIGS. 10A and 10B.

Aside from sensors, one or more light emitting diodes (LEDs) may beutilized to provide lighting within the imaging hood 12. Althoughillumination may be provided by optical fibers routed through deploymentcatheter 16, the use of LEDs over the imaging hood 12 may eliminate theneed for additional optical fibers for providing illumination. Theelectrical wires connected to the one or more LEDs may be routed throughor over the hood 12 and along an exterior surface or extruded withindeployment catheter 16. One or more LEDs may be positioned in acircumferential pattern 306 around imaging hood 12, as shown in FIG.25A, or in a linear longitudinal pattern 308 along imaging hood 12, asshown in FIG. 25B. Other patterns, such as a helical or spiral pattern,may also be utilized. Alternatively, LEDs may be positioned along asupport member forming part of imaging hood 12.

In another alternative for illumination within imaging hood 12, aseparate illumination tool 310 may be utilized, as shown in FIG. 26A. Anexample of such a tool may comprise a flexible intravascular deliverymember 312 having a carrier member 314 pivotably connected 316 to adistal end of delivery member 312. One or more LEDs 318 may be mountedalong carrier member 314. In use, delivery member 312 may be advancedthrough deployment catheter 16 until carrier member 314 is positionedwithin imaging hood 12. Once within imaging hood 12, carrier member 314may be pivoted in any number of directions to facilitate or optimize theillumination within the imaging hood 12, as shown in FIG. 26B.

In utilizing LEDs for illumination, whether positioned along imaginghood 12 or along a separate instrument, the LEDs may comprise a singleLED color, e.g., white light. Alternatively, LEDs of other colors, e.g.,red, blue, yellow, etc., may be utilized exclusively or in combinationwith white LEDs to provide for varied illumination of the tissue orfluids being imaged. Alternatively, sources of infrared or ultravioletlight may be employed to enable imaging beneath the tissue surface orcause fluorescence of tissue for use in system guidance, diagnosis, ortherapy.

Aside from providing a visualization platform, the imaging assembly mayalso be utilized to provide a therapeutic platform for treating tissuebeing visualized. As shown in FIG. 27, deployment catheter 320 may haveimaging hood 322, as described above, and fluid delivery lumen 324 andimaging lumen 326. In this variation, a therapeutic tool such as needle328 may be delivered through fluid delivery lumen 324 or in anotherworking lumen and advanced through open area 332 for treating the tissuewhich is visualized. In this instance, needle 328 may define one orseveral ports 330 for delivering drugs therethrough. Thus, once theappropriate region of tissue has been imaged and located, needle 328 maybe advanced and pierced into the underlying tissue where a therapeuticagent may be delivered through ports 330. Alternatively, needle 328 maybe in electrical communication with a power source 334, e.g.,radio-frequency, microwave, etc., for ablating the underlying tissuearea of interest.

FIG. 28 shows another alternative in which deployment catheter 340 mayhave imaging hood 342 attached thereto, as above, but with a therapeutictool 344 in the configuration of a helical tissue piercing device 344.Also shown and described above in FIGS. 7A and 7B for use in stabilizingthe imaging hood relative to the underlying tissue, the helical tissuepiercing device 344 may also be utilized to manipulate the tissue for avariety of therapeutic procedures. The helical portion 346 may alsodefine one or several ports for delivery of therapeutic agentstherethrough.

In yet another alternative, FIG. 29 shows a deployment catheter 350having an expandable imaging balloon 352 filled with, e.g., saline 356.A therapeutic tool 344, as above, may be translatable relative toballoon 352. To prevent the piercing portion 346 of the tool fromtearing balloon 352, a stop 354 may be formed on balloon 352 to preventthe proximal passage of portion 346 past stop 354.

Alternative configurations for tools which may be delivered throughdeployment catheter 16 for use in tissue manipulation within imaginghood 12 are shown in FIGS. 30A and 30B. FIG. 30A shows one variation ofan angled instrument 360, such as a tissue grasper, which may beconfigured to have an elongate shaft for intravascular delivery throughdeployment catheter 16 with a distal end which may be angled relative toits elongate shaft upon deployment into imaging hood 12. The elongateshaft may be configured to angle itself automatically, e.g., by theelongate shaft being made at least partially from a shape memory alloy,or upon actuation, e.g., by tensioning a pullwire. FIG. 30B showsanother configuration for an instrument 362 being configured toreconfigure its distal portion into an off-axis configuration withinimaging hood 12. In either case, the instruments 360, 362 may bereconfigured into a low-profile shape upon withdrawing them proximallyback into deployment catheter 16.

Other instruments or tools which may be utilized with the imaging systemis shown in the side and end views of FIGS. 31A to 31C. FIG. 31A shows aprobe 370 having a distal end effector 372, which may be reconfiguredfrom a low-profile shape to a curved profile. The end effector 372 maybe configured as an ablation probe utilizing radio-frequency energy,microwave energy, ultrasound energy, laser energy or even cryo-ablation.Alternatively, the end effector 372 may have several electrodes upon itfor detecting or mapping electrical signals transmitted through theunderlying tissue.

In the case of an end effector 372 utilized for ablation of theunderlying tissue, an additional temperature sensor such as athermocouple or thermistor 374 positioned upon an elongate member 376may be advanced into the imaging hood 12 adjacent to the distal endeffector 372 for contacting and monitoring a temperature of the ablatedtissue. FIG. 31B shows an example in the end view of one configurationfor the distal end effector 372 which may be simply angled into aperpendicular configuration for contacting the tissue. FIG. 31C showsanother example where the end effector may be reconfigured into a curvedend effector 378 for increased tissue contact.

FIGS. 32A and 32B show another variation of an ablation tool utilizedwith an imaging hood 12 having an enclosed bottom portion. In thisvariation, an ablation probe, such as a cryo-ablation probe 380 having adistal end effector 382, may be positioned through the imaging hood 12such that the end effector 382 is placed distally of a transparentmembrane or enclosure 384, as shown in the end view of FIG. 32B. Theshaft of probe 380 may pass through an opening 386 defined through themembrane 384. In use, the clear fluid may be pumped into imaging hood12, as described above, and the distal end effector 382 may be placedagainst a tissue region to be ablated with the imaging hood 12 and themembrane 384 positioned atop or adjacent to the ablated tissue. In thecase of cryo-ablation, the imaging fluid may be warmed prior todispensing into the imaging hood 12 such that the tissue contacted bythe membrane 384 may be warmed during the cryo-ablation procedure. Inthe case of thermal ablation, e.g., utilizing radio-frequency energy,the fluid dispensed into the imaging hood 12 may be cooled such that thetissue contacted by the membrane 384 and adjacent to the ablation probeduring the ablation procedure is likewise cooled.

In either example described above, the imaging fluid may be varied inits temperature to facilitate various procedures to be performed uponthe tissue. In other cases, the imaging fluid itself may be altered tofacilitate various procedures. For instance as shown in FIG. 33A, adeployment catheter 16 and imaging hood 12 may be advanced within ahollow body organ, such as a bladder filled with urine 394, towards alesion or tumor 392 on the bladder wall. The imaging hood 12 may beplaced entirely over the lesion 392, or over a portion of the lesion.Once secured against the tissue wall 390, a cryo-fluid, i.e., a fluidwhich has been cooled to below freezing temperatures of, e.g., water orblood, may be pumped into the imaging hood 12 to cryo-ablate the lesion390, as shown in FIG. 33B while avoiding the creation of ice on theinstrument or surface of tissue.

As the cryo-fluid leaks out of the imaging hood 12 and into the organ,the fluid may be warmed naturally by the patient body and ultimatelyremoved. The cryo-fluid may be a colorless and translucent fluid whichenables visualization therethrough of the underlying tissue. An exampleof such a fluid is Fluorinert™ (3M, St. Paul, Minn.), which is acolorless and odorless perfluorinated liquid. The use of a liquid suchas Fluorinert™ enables the cryo-ablation procedure without the formationof ice within or outside of the imaging hood 12. Alternatively, ratherthan utilizing cryo-ablation, hyperthermic treatments may also beeffected by heating the Fluorinert™ liquid to elevated temperatures forablating the lesion 392 within the imaging hood 12. Moreover,Fluorinert™ may be utilized in various other parts of the body, such aswithin the heart.

FIG. 34A shows another variation of an instrument which may be utilizedwith the imaging system. In this variation, a laser ring generator 400may be passed through the deployment catheter 16 and partially intoimaging hood 12. A laser ring generator 400 is typically used to createa circular ring of laser energy 402 for generating a conduction blockaround the pulmonary veins typically in the treatment of atrialfibrillation. The circular ring of laser energy 402 may be generatedsuch that a diameter of the ring 402 is contained within a diameter ofthe imaging hood 12 to allow for tissue ablation directly upon tissuebeing imaged. Signals which cause atrial fibrillation typically comefrom the entry area of the pulmonary veins into the left atrium andtreatments may sometimes include delivering ablation energy to the ostiaof the pulmonary veins within the atrium. The ablated areas of thetissue may produce a circular scar which blocks the impulses for atrialfibrillation.

When using the laser energy to ablate the tissue of the heart, it may begenerally desirable to maintain the integrity and health of the tissueoverlying the surface while ablating the underlying tissue. This may beaccomplished, for example, by cooling the imaging fluid to a temperaturebelow the body temperature of the patient but which is above thefreezing point of blood (e.g., 2° C. to 35° C.). The cooled imagingfluid may thus maintain the surface tissue at the cooled fluidtemperature while the deeper underlying tissue remains at the patientbody temperature. When the laser energy (or other types of energy suchas radio frequency energy, microwave energy, ultrasound energy, etc.)irradiates the tissue, both the cooled tissue surface as well as thedeeper underlying tissue will rise in temperature uniformly. The deeperunderlying tissue, which was maintained at the body temperature, willincrease to temperatures which are sufficiently high to destroy theunderlying tissue. Meanwhile, the temperature of the cooled surfacetissue will also rise but only to temperatures that are near bodytemperature or slightly above.

Accordingly, as shown in FIG. 34B, one example for treatment may includepassing deployment catheter 16 across the atrial septum AS and into theleft atrium LA of the patient's heart H. Other methods of accessing theleft atrium LA may also be utilized. The imaging hood 12 and laser ringgenerator 400 may be positioned adjacent to or over one or more of theostium OT of the pulmonary veins PV and the laser generator 400 mayablate the tissue around the ostium OT with the circular ring of laserenergy 402 to create a conduction block. Once one or more of the tissuearound the ostium OT have been ablated, the imaging hood 12 may bereconfigured into a low profile for removal from the patient heart H.

One of the difficulties in treating tissue in or around the ostium OT isthe dynamic fluid flow of blood through the ostium OT. The dynamicforces make cannulation or entry of the ostium OT difficult. Thus,another variation on instruments or tools utilizable with the imagingsystem is an extendible cannula 410 having a cannula lumen 412 definedtherethrough, as shown in FIG. 35A. The extendible cannula 410 maygenerally comprise an elongate tubular member which may be positionedwithin the deployment catheter 16 during delivery and then projecteddistally through the imaging hood 12 and optionally beyond, as shown inFIG. 35B.

In use, once the imaging hood 12 has been desirably positioned relativeto the tissue, e.g., as shown in FIG. 35C outside the ostium OT of apulmonary vein PV, the extendible cannula 410 may be projected distallyfrom the deployment catheter 16 while optionally imaging the tissuethrough the imaging hood 12, as described above. The extendible cannula410 may be projected distally until its distal end is extended at leastpartially into the ostium OT. Once in the ostium OT, an instrument orenergy ablation device may be extended through and out of the cannulalumen 412 for treatment within the ostium OT. Upon completion of theprocedure, the cannula 410 may be withdrawn proximally and removed fromthe patient body. The extendible cannula 410 may also include aninflatable occlusion balloon at or near its distal end to block theblood flow out of the PV to maintain a clear view of the tissue region.Alternatively, the extendible cannula 410 may define a lumentherethrough beyond the occlusion balloon to bypass at least a portionof the blood that normally exits the pulmonary vein PV by directing theblood through the cannula 410 to exit proximal of the imaging hood.

Yet another variation for tool or instrument use may be seen in the sideand end views of FIG. 36A and 36B. In this variation, imaging hood 12may have one or more tubular support members 420 integrated with thehood 12. Each of the tubular support members 420 may define an accesslumen 422 through which one or more instruments or tools may bedelivered for treatment upon the underlying tissue. One particularexample is shown and described above for FIG. 7C.

Various methods and instruments may be utilized for using orfacilitating the use of the system. For instance, one method may includefacilitating the initial delivery and placement of a device into thepatient's heart. In initially guiding the imaging assembly within theheart chamber to, e.g., the mitral valve MV, a separate guiding probe430 may be utilized, as shown in FIGS. 37A and 37B. Guiding probe 430may, for example, comprise an optical fiber through which a light source434 may be used to illuminate a distal tip portion 432. The tip portion432 may be advanced into the heart through, e.g., the coronary sinus CS,until the tip is positioned adjacent to the mitral valve MV. The tip 432may be illuminated, as shown in FIG. 37A, and imaging assembly 10 maythen be guided towards the illuminated tip 432, which is visible fromwithin the atrial chamber, towards mitral valve MV.

Aside from the devices and methods described above, the imaging systemmay be utilized to facilitate various other procedures. Turning now toFIGS. 38A and 38B, the imaging hood of the device in particular may beutilized. In this example, a collapsible membrane or disk-shaped member440 may be temporarily secured around the contact edge or lip of imaginghood 12. During intravascular delivery, the imaging hood 12 and theattached member 440 may both be in a collapsed configuration to maintaina low profile for delivery. Upon deployment, both the imaging hood 12and the member 440 may extend into their expanded configurations.

The disk-shaped member 440 may be comprised of a variety of materialsdepending upon the application. For instance, member 440 may befabricated from a porous polymeric material infused with a drug elutingmedicament 442 for implantation against a tissue surface for slowinfusion of the medicament into the underlying tissue. Alternatively,the member 440 may be fabricated from a non-porous material, e.g., metalor polymer, for implantation and closure of a wound or over a cavity toprevent fluid leakage. In yet another alternative, the member 440 may bemade from a distensible material which is secured to imaging hood 12 inan expanded condition. Once implanted or secured on a tissue surface orwound, the expanded member 440 may be released from imaging hood 12.Upon release, the expanded member 440 may shrink to a smaller size whileapproximating the attached underlying tissue, e.g., to close a wound oropening.

One method for securing the disk-shaped member 440 to a tissue surfacemay include a plurality of tissue anchors 444, e.g., barbs, hooks,projections, etc., which are attached to a surface of the member 440.Other methods of attachments may include adhesives, suturing, etc. Inuse, as shown in FIGS. 39A to 39C, the imaging hood 12 may be deployedin its expanded configuration with member 440 attached thereto with theplurality of tissue anchors 444 projecting distally. The tissue anchors444 may be urged into a tissue region to be treated 446, as seen in FIG.39A, until the anchors 444 are secured in the tissue and member 440 ispositioned directly against the tissue, as shown in FIG. 39B. A pullwiremay be actuated to release the member 440 from the imaging hood 12 anddeployment catheter 16 may be withdrawn proximally to leave member 440secured against the tissue 446.

Another variation for tissue manipulation and treatment may be seen inthe variation of FIG. 40A, which illustrates an imaging hood 12 having adeployable anchor assembly 450 attached to the tissue contact edge 22.FIG. 40B illustrates the anchor assembly 450 detached from the imaginghood 12 for clarity. The anchor assembly 450 may be seen as having aplurality of discrete tissue anchors 456, e.g., barbs, hooks,projections, etc., each having a suture retaining end, e.g., an eyeletor opening 458 in a proximal end of the anchors 456. A suture member orwire 452 may be slidingly connected to each anchor 456 through theopenings 458 and through a cinching element 454, which may be configuredto slide uni-directionally over the suture or wire 452 to approximateeach of the anchors 456 towards one another. Each of the anchors 456 maybe temporarily attached to the imaging hood 12 through a variety ofmethods. For instance, a pullwire or retaining wire may hold each of theanchors within a receiving ring around the circumference of the imaginghood 12. When the anchors 456 are released, the pullwire or retainingwire may be tensioned from its proximal end outside the patient body tothereby free the anchors 456 from the imaging hood 12.

One example for use of the anchor assembly 450 is shown in FIGS. 41A to41D for closure of an opening or wound 460, e.g., patent foramen ovale(PFO). The deployment catheter 16 and imaging hood 12 may be deliveredintravascularly into, e.g., a patient heart. As the imaging hood 12 isdeployed into its expanded configuration, the imaging hood 12 may bepositioned adjacent to the opening or wound 460, as shown in FIG. 41A.With the anchor assembly 450 positioned upon the expanded imaging hood12, deployment catheter 16 may be directed to urge the contact edge ofimaging hood 12 and anchor assembly 450 into the region surrounding thetissue opening 460, as shown in FIG. 41B. Once the anchor assembly 450has been secured within the surrounding tissue, the anchors may bereleased from imaging hood 12 leaving the anchor assembly 450 and suturemember 452 trailing from the anchors, as shown in FIG. 41C. The sutureor wire member 452 may be tightened by pulling it proximally fromoutside the patient body to approximate the anchors of anchor assembly450 towards one another in a purse-string manner to close the tissueopening 462, as shown in FIG. 41D. The cinching element 454 may also bepushed distally over the suture or wire member 452 to prevent theapproximated anchor assembly 450 from loosening or widening.

Another example for an alternative use is shown in FIG. 42, where thedeployment catheter 16 and deployed imaging hood 12 may be positionedwithin a patient body for drawing blood 472 into deployment catheter 16.The drawn blood 472 may be pumped through a dialysis unit 470 locatedexternally of the patient body for filtering the drawn blood 472 and thefiltered blood may be reintroduced back into the patient.

Yet another variation is shown in FIGS. 43A and 43B, which show avariation of the deployment catheter 480 having a first deployable hood482 and a second deployable hood 484 positioned distal to the first hood482. The deployment catheter 480 may also have a side-viewing imagingelement 486 positioned between the first and second hoods 482, 484 alongthe length of the deployment catheter 480. In use, such a device may beintroduced through a lumen 488 of a vessel VS, where one or both hoods482, 484 may be expanded to gently contact the surrounding walls ofvessel VS. Once hoods 482, 484 have been expanded, the clear imagingfluid may be pumped in the space defined between the hoods 482, 484 todisplace any blood and to create an imaging space 490, as shown in FIG.43B. With the clear fluid in-between hoods 482, 484, the imaging element486 may be used to view the surrounding tissue surface contained betweenhoods 482, 484. Other instruments or tools may be passed throughdeployment catheter 480 and through one or more openings defined alongthe catheter 480 for additionally performing therapeutic procedures uponthe vessel wall.

Another variation of a deployment catheter 500 which may be used forimaging tissue to the side of the instrument may be seen in FIGS. 44A to45B. FIGS. 44A and 44B show side and end views of deployment catheter500 having a side-imaging balloon 502 in an un-inflated low-profileconfiguration. A side-imaging element 504 may be positioned within adistal portion of the catheter 500 where the balloon 502 is disposed.When balloon 502 is inflated, it may expand radially to contact thesurrounding tissue, but where the imaging element 504 is located, avisualization field 506 may be created by the balloon 502, as shown inthe side, top, and end views of FIGS. 45A to 45B, respectively. Thevisualization field 506 may simply be a cavity or channel which isdefined within the inflated balloon 502 such that the visualizationelement 504 is provided an image of the area within field 506 which isclear and unobstructed by balloon 502.

In use, deployment catheter 500 may be advanced intravascularly throughvessel lumen 488 towards a lesion or tumor 508 to be visualized and/ortreated. Upon reaching the lesion 508, deployment catheter 500 may bepositioned adjacently to the lesion 508 and balloon 502 may be inflatedsuch that the lesion 508 is contained within the visualization field506. Once balloon 502 is fully inflated and in contact against thevessel wall, clear fluid may be pumped into visualization field 506through deployment catheter 500 to displace any blood or opaque fluidsfrom the field 506, as shown in the side and end views of FIGS. 46A and46B, respectively. The lesion 508 may then be visually inspected andtreated by passing any number of instruments through deployment catheter500 and into field 506.

In additional variations of the imaging hood and deployment catheter,the various assemblies may be configured in particular for treatingconditions such as atrial fibrillation while under direct visualization.In particular, the devices and assemblies may be configured tofacilitate the application of energy to the underlying tissue in acontrolled manner while directly visualizing the tissue to monitor aswell as confirm appropriate treatment. Generally, as illustrated inFIGS. 47A to 470, the imaging and manipulation assembly may be advancedintravascularly into the patient's heart H, e.g., through the inferiorvena cava IVC and into the right atrium RA, as shown in FIGS. 47A and47B. Within the right atrium RA (or prior to entering), hood 12 may bedeployed and positioned against the atrial septum AS and the hood 12 maybe infused with saline to clear the blood from within to view theunderlying tissue surface, as described above. Hood 12 may be furthermanipulated or articulated into a desirable location along the tissuewall, e.g., over the fossa ovalis FO, for puncturing through to the leftatrium LA, as shown in FIG. 47C.

Once the hood 12 has been desirably positioned over the fossa ovalis FO,a piercing instrument 510, e.g., a hollow needle, may be advanced fromcatheter 16 and through hood 12 to pierce through the atrial septum ASuntil the left atrium LA has been accessed, as shown in FIG. 47D. Aguidewire 17 may then be advanced through the piercing instrument 510and introduced into the left atrium LA, where it may be further advancedinto one of the pulmonary veins PV, as shown in FIG. 47E. With theguidewire 17 crossing the atrial septum AS into the left atrium LA, thepiercing instrument 510 may be withdrawn, as shown in FIG. 47F, or thehood 12 may be further retracted into its low profile configuration andcatheter 16 and sheath 14 may be optionally withdrawn as well whileleaving the guidewire 17 in place crossing the atrial septum AS, asshown in FIG. 47G.

Although one example is illustrated for crossing through the septal wallwhile under direct visualization, alternative methods and devices fortransseptal access are shown and described in further detail in commonlyowned U.S. patent application Ser. No. 11/763,399 filed Jun. 14, 2007,which is incorporated herein by reference in its entirety. Thosetransseptal access methods and devices may be fully utilized with themethods and devices described herein, as practicable.

If sheath 14 is left in place within the inferior vena cava IVC, anoptional dilator 512 may be advanced through sheath 14 and alongguidewire 17, as shown in FIG. 47H, where it may be used to dilate thetransseptal puncture through the atrial septum AS to allow for otherinstruments to be advanced transseptally into the left atrium LA, asshown in FIG. 47I. With the transseptal opening dilated, hood 12 in itslow profile configuration and catheter 16 may be re-introduced throughsheath 16 over guidewire 17 and advanced transseptally into the leftatrium LA, as shown in FIG. 47J. Optionally, guidewire 17 may bewithdrawn prior to or after introduction of hood 12 into the left atriumLA. With hood 12 advanced into and expanded within the left atrium LA,as shown in FIG. 47K, deployment catheter 16 and/or hood 12 may bearticulated to be placed into contact with or over the ostia of thepulmonary veins PV, as shown in FIG. 47L. Once hood 12 has beendesirably positioned along the tissue surrounding the pulmonary veins,the open area within hood 12 may be cleared of blood with thetranslucent or transparent fluid for directly visualizing the underlyingtissue such that the tissue may be ablated, as indicated by thecircumferentially ablated tissue 514 about the ostium of the pulmonaryveins shown in FIG. 47M. One or more of the ostia may be ablated eitherpartially or entirely around the opening to create a conduction block,as shown respectively in FIGS. 47N and 47O.

Because the hood 12 allows for direct visualization of the underlyingtissue in vivo, hood 12 may be used to visually confirm that theappropriate regions of tissue have been ablated and/or that the tissuehas been sufficiently ablated. Visual monitoring and confirmation may beaccomplished in real-time during a procedure or after the procedure hasbeen completed. Additionally, hood 12 may be utilized post-operativelyto image tissue which has been ablated in a previous procedure todetermine whether appropriate tissue ablation had been accomplished. Inthe partial cross-sectional views of FIGS. 48A and 48B, hood 12 is shownadvanced into the left atrium LA to examine discontiguous lesions 520which have been made around an ostium of a pulmonary vein PV. If desiredor determined to be necessary, the untreated tissue may be furtherablated under direct visualization utilizing hood 12.

To ablate the tissue visualized within hood 12, a number of variousablation instruments may be utilized. In particular, an ablation probe534 having at least one ablation electrode 536 utilizing, e.g.,radio-frequency (RF), microwave, ultrasound, laser, cryo-ablation, etc.,may be advanced through deployment catheter 16 and into the open area 26of hood 12, as shown in the perspective view of FIG. 49A. Hood 12 isalso shown with several support struts 530 extending longitudinallyalong hood 12 to provide structural support as well as to provide aplatform upon which imaging element 532 may be positioned. As describedabove, imaging element 532 may comprise a number of imaging devices,such as optical fibers or electronic imagers such as CCD or CMOSimagining elements. In either case, imaging element 532 may bepositioned along a support strut 530 off-axis relative to a longitudinalaxis of catheter 16 such that element 532 is angled to provide a visualfield of the underlying tissue and ablation probe 536. Moreover, thedistal portion of ablation probe 536 may be configured to be angled orarticulatable such that probe 536 may be positioned off-axis relative tothe longitudinal axis of catheter 16 to allow for probe 536 to reachover the area of tissue visualized within open field 26 and to alsoallow for a variety of lesion patterns depending upon the desiredtreatment.

FIGS. 49B and 49C show side and perspective views, respectively, of hood12 placed against a tissue region T to be treated where the translucentor transparent displacing fluid 538 is injected into the open area 26 ofhood 12 to displace the blood therewithin. While under directvisualization from imaging element 532, the blood may be displaced withthe clear fluid to allow for inspection of the tissue T, whereuponablation probe 536 may be activated and/or optionally angled to contactthe underlying tissue for treatment.

FIG. 50A shows a perspective view of a variation of the ablation probewhere a distal end effector 542 of the probe 540 may be angled alongpivoting hinge 544 from a longitudinal low-profile configuration to aright-angled straight electrode to provide for linear transmurallesions. Probe 540 is similarly configured to the variation shown inFIGS. 31A and 31B above. Utilizing this configuration, an entire line oftissue can be ablated simultaneously rather than a spot of tissue beingablated. FIG. 50B shows another variation where an ablation probe 546may be configured to have a circularly-shaped ablation end effector 548which circumscribes the opening of hood 12. This particular variation isalso similarly configured to the variation shown above in FIG. 31C. Thediameter of the probe 548 may be varied and other circular or ellipticalconfigurations, as well as partially circular configurations, may beutilized to provide for the ablation of an entire ring of tissue.

While ablating the tissue, the saline flow from the hood 12 can becontrolled such that the saline is injected over the heated electrodesafter every ablation process to cool the electrodes. This is a safetymeasure which may be optionally implemented to prevent a heatedelectrode from undesirably ablating other regions of the tissueinadvertently.

In yet another variation for ablating underlying tissue while underdirect visualization, FIG. 51A shows an embodiment of hood 12 having anexpandable distal membrane 550 covering the open area of hood 12. Acircularly-shaped RF electrode end effector 552 having electrodes 554spaced between insulating sections 556 may be coated or otherwisedisposed, e.g., by chemical vapor deposition or any other suitableprocess, circumferentially around the expandable distal membrane 550.The electrode end effector 552 may be energized by an external powersource which is in electrical communication by wires 558. Moreover,electrode end effector 552 may be retractable into the work channels ofdeployment catheter 16. Imaging element 532 may be attached to a supportstrut of the hood 12 to provide the visualization during the ablationprocess, as described above, for viewing through the clear fluid infusedwithin hood 12. FIG. 51B shows a similar variation where an inflatableballoon 560 is utilized and hood 12 has been omitted entirely. In thiscase, electrode end effector 552 may be disposed circumferentially overthe balloon distal end in a similar manner.

In either variation, circular transmural lesions may be created byinflating infusing saline into hood 12 to extend membrane 550 ordirectly into balloon 560 such that pressure may be exerted upon thecontacted target tissue, such as the pulmonary ostia area, by the endeffector 552 which may then be energized to channel energy to theablated tissue for lesion formation. The amount of power delivered toeach electrode end effector 552 can be varied and controlled to enablethe operator to ablate areas where different segments of the tissue mayhave different thicknesses, hence requiring different amounts of powerto create a lesion.

FIG. 52 illustrates a perspective view of another variation having acircularly-shaped electrode end effector 570 with electrodes 572 spacedbetween insulating sections 574 and disposed circumferentially aroundthe contact lip or edge of hood 12. This variation is similar to theconfiguration shown above in FIG. 22A. Although described above forelectrode mapping of the underlying tissue, electrode end effector 570in this variation may be utilized to contact the tissue and to createcircularly-shaped lesions around the target tissue.

In utilizing the imaging hood 12 in any one of the procedures describedherein, the hood 12 may have an open field which is uncovered and clearto provide direct tissue contact between the hood interior and theunderlying tissue to effect any number of treatments upon the tissue, asdescribed above. Yet in additional variations, imaging hood 12 mayutilize other configurations, as also described above. An additionalvariation of the imaging hood 12 is shown in the perspective and sideviews, respectively, of FIGS. 53A and 53B, where imaging hood 12includes at least one layer of a transparent elastomeric membrane 580over the distal opening of hood 12. An aperture 582 having a diameterwhich is less than a diameter of the outer lip of imaging hood 12 may bedefined over the center of membrane 580 where a longitudinal axis of thehood intersects the membrane such that the interior of hood 12 remainsopen and in fluid communication with the environment external to hood12. Furthermore, aperture 582 may be sized, e.g., between 1 to 2 mm ormore in diameter and membrane 580 be made from any number of transparentelastomers such as silicone, polyurethane, latex, etc. such thatcontacted tissue may also be visualized through membrane 580 as well asthrough aperture 582.

Aperture 582 may function generally as a restricting passageway toreduce the rate of fluid out-flow from the hood 12 when the interior ofthe hood 12 is infused with the clear fluid through which underlyingtissue regions may be visualized. Aside from restricting out-flow ofclear fluid from within hood 12, aperture 582 may also restrict externalsurrounding fluids from entering hood 12 too rapidly. The reduction inthe rate of fluid out-flow from the hood and blood in-flow into the hoodmay improve visualization conditions as hood 12 may be more readilyfilled with transparent fluid rather than being filled by opaque bloodwhich may obstruct direct visualization by the visualizationinstruments.

Moreover, aperture 582 may be aligned with catheter 16 such that anyinstruments (e.g., piercing instruments, guidewires, tissue engagers,etc.) that are advanced into the hood interior may directly access theunderlying tissue uninhibited or unrestricted for treatment throughaperture 582. In other variations wherein aperture 582 may not bealigned with catheter 16, instruments passed through catheter 16 maystill access the underlying tissue by simply piercing through membrane580.

FIG. 54A shows yet another variation where a single RF ablation probe590 may be inserted through the work channel of the tissue visualizationcatheter in its closed configuration where a first half 592 and a secondhalf 594 are closed with respect to one another. Upon actuation, such asby pull wires, first half 592 and second half 594 may open up laterallyvia a hinged pivot 602 into a “Y” configuration to expose an ablationelectrode strip 596 connected at attachment points 598, 600 to halves592, 594, respectively and as shown in the perspective view of FIG. 54B.Tension is created along the axis of the electrode strip 596 to maintainits linear configuration. Linear transmural lesion ablation may be thenaccomplished by channeling energy from the RF electrode to the targettissue surface in contact while visualized within hood 12.

FIGS. 55A and 55B illustrate perspective views of another variationwhere a laser probe 610, e.g., an optical fiber bundle coupled to alaser generator, may be inserted through the work channel of the tissuevisualization catheter. When actuated, laser energy 612 may be channeledthrough probe 610 and applied to the underlying tissue T at differentangles 612′ to form a variety of lesion patterns, as shown in FIG. 55C.

When treating the tissue in vivo around the ostium OT of a pulmonaryvein for atrial fibrillation, occluding the blood flow through thepulmonary veins PV may facilitate the visualization and stabilization ofhood 12 with respect to the tissue, particularly when applying ablationenergy. In one variation, with hood 12 expanded within the left atriumLA, guidewire 17 may be advanced into the pulmonary vein PV to betreated. An expandable occlusion balloon 620, either advanced overguidewire 17 or carried directly upon guidewire 17, may be advanced intothe pulmonary vein PV distal to the region of tissue to be treated whereit may then be expanded into contact with the walls of the pulmonaryvein PV, as shown in FIG. 56. With occlusion balloon 620 expanded, thevessel may be occluded and blood flow temporarily halted from enteringthe left atrium LA. Hood 12 may then be positioned along or around theostium OT and the contained space encompassed between the hood 12 andocclusion balloon 620 may be infused with the clear fluid 528 to createa cleared visualization area 622 within which the ostium OT andsurrounding tissue may be visualized via imaging element 532 andaccordingly treated using any of the ablation instruments describedherein, as practicable.

Aside from use of an occlusion balloon, articulation and manipulation ofhood 12 within a beating heart with dynamic fluid currents may befurther facilitated utilizing support members. In one variation, one ormore grasping support members may be passed through catheter 16 anddeployed from hood 12 to allow for the hood 12 to be walked or movedalong the tissue surfaces of the heart chambers. FIG. 57 shows aperspective view of hood 12 with a first tissue grasping support member630 having a first tissue grasper 634 positioned at a distal end ofmember 630. A distal portion of member 630 may be angled via firstangled or curved portion 632 to allow for tissue grasper 634 to moredirectly approach and adhere onto the tissue surface. Similarly, secondtissue grasping support member 636 may extend through hood 12 withsecond angled or curved portion 638 and second tissue grasper 640positioned at a distal end of member 638. Although illustrated in thisvariation as a helical tissue engager, other tissue grasping mechanismsmay be alternatively utilized.

As illustrated in FIGS. 58A to 58C, with hood 12 expanded within theleft atrium LA, first and second tissue graspers 634, 640 may bedeployed and advanced distally of hood 12. First tissue grasper 634 maybe advanced into contact with a first tissue region adjacent to theostium OT and torqued until grasper 634 is engaged to the tissue, asshown in FIG. 58A. With grasper 634 temporarily adhered to the tissue,second tissue grasper 640 may be moved and positioned against a tissueregion adjacent to first tissue grasper 636 where it may then be torquedand temporarily adhered to the tissue, as shown in FIG. 58B. With secondgrasper 640 now adhered to the tissue, first grasper 636 may be releasedfrom the tissue and hood 12 and first tissue grasper 636 may be angledto another region of tissue utilizing first second grasper 640 as apivoting point to facilitate movement of hood 12 along the tissue wall,as shown in FIG. 58C. This process may be repeated as many times asdesired until hood 12 has been positioned along a tissue region to betreated or inspected.

FIG. 59 shows another view illustrating first tissue grasper 634extended from hood 12 and temporarily engaged onto the tissue adjacentto the pulmonary vein, specifically the right inferior pulmonary veinPV_(RI) which is generally difficult to access in particular because ofits close proximity and tight angle relative to the transseptal point ofentry through the atrial septum AS into the left atrium LA. Withcatheter 16 retroflexed to point hood 12 generally in the direction ofthe right inferior pulmonary vein PV_(RI) and with first tissue grasper634 engaged onto the tissue, hood 12 and deployment catheter 16 may beapproximated towards the right inferior pulmonary vein ostium with thehelp of the grasper 634 to inspect and/or treat the tissue.

FIG. 60 illustrates an alternative method for the tissue visualizationcatheter to access the left atrium LA of the heart H to inspect and/ortreat the areas around the pulmonary veins PV. Using an intravasculartrans-femoral approach, deployment catheter 16 may be advanced throughthe aorta AO, through the aortic valve AV and into the left ventricleLV, through the mitral valve MV and into the left atrium LA. Once withinthe left ventricle LV, a helical tissue grasper 84 may be extendedthrough hood 12 and into contact against the desired tissue region tofacilitate inspection and/or treatment.

When utilizing the tissue grasper to pull hood 12 and catheter 16towards the tissue region for inspection or treatment, adequate forcetransmission to articulate and further advance the catheter 16 may beinhibited by the tortuous configuration of the catheter 16. Accordingly,the first tissue grasper 634 can be used optionally to loop a length ofwire or suture 650 affixed to one end of hood 12 and through the securedend of the first grasper 634, as shown in FIG. 61A. The suture 650,routed through catheter 16, can be subsequently pulled from its proximalend from outside the patient body (as indicated by the direction oftension 652) to provide additional pulling strength for the catheter 16to move distally along the length of member 630 like a pulley system (asindicated by the direction of hood movement 654, as illustrated in FIG.61B. FIGS. 61C and 61D further illustrate the tightly-angledconfiguration which catheter 16 and hood 12 must conform to and therelative movement of tensioned suture 650 with the resulting directionof movement 654 of hood 12 into position against the ostium OT. Undersuch a pulley mechanism, the hood 12 may also provide additionalpressure on the target tissue to provide a better seal between the hood12 and the tissue surface.

In yet another variation for the ablation treatment of intra-atrialtissue, FIG. 62A shows sheath 14 positioned transseptally with atransparent intra-atrial balloon 660 inflated to such a size as tooccupy a relatively large portion of the atrial chamber, e.g., 75% ormore of the volume of the left atrium LA. Balloon 660 may be inflated bya clear fluid such as saline or a gas. Visualization of tissue surfacesin contact against the intra-atrial balloon 660 becomes possible asbodily opaque fluids, such as blood, is displaced by the balloon 660. Itmay also be possible to visualize and identify a number of ostia of thepulmonary veins PV through balloon 660. With the position of thepulmonary veins PV identified, the user may orient instruments insidethe cardiac chamber by using the pulmonary veins PV as anatomicallandmarks.

FIGS. 62B and 62C illustrate an imaging instrument, such as a fiberscope662, advanced at least partially within the intra-atrial balloon 660 tosurvey the cardiac chamber as well as articulating the fiberscope 662 toobtain closer images of tissue regions of interest as well as tonavigate a wide range of motion. FIG. 62D illustrates a variation ofballoon 660 where one or more radio-opaque fiducial markers 664 may bepositioned over the balloon such that a position and inflation size ofthe balloon 660 may be tracked or monitored by extracorporeal imagingmodalities, such as fluoroscopy, magnetic resonance imaging, computedtomography, etc.

With balloon 660 inflated and pressed against the atrial tissue wall, inorder to access and treat a tissue region of interest within thechamber, a needle catheter 666 having a piercing ablation tip 668 may beadvanced through a lumen of the deployment catheter and into theinterior of the balloon 660. The needle catheter 666 may be articulatedto direct the ablation tip 668 to the tissue to be treated and theablation tip 668 may be simply advanced to pierce through the balloon660 and into the underlying tissue, where ablation treatment may beeffected, as shown in FIG. 63. Provided that the needles projecting fromablation tip 668 are sized sufficiently small in diameter and are gentlyinserted through the balloon 660, leakage or bursting of the balloon 660may be avoided. Alternatively, balloon 660 may be fabricated from aporous material such that the injected clear fluid, such as saline, maydiffuse out of the balloon 660 to provide a medium for RF tissueablation by enabling a circuit between the positive and negativeelectrode to be closed through the balloon wall by allowing the diffusedsaline to be an intermediate conductor. Other ablation instruments suchas laser probes can also be utilized and inserted from within theballoon 660 to access the tissue region to be treated.

FIGS. 64A and 64B illustrate detail views of a safety feature where oneor more ablation probes 672 are deployable from a retractedconfiguration, as shown in FIG. 64A, where each probe is hidden itsrespective opening 670 when unused. This prevents an unintendedpenetration of the balloon 660 or inadvertent ablation to surroundingtissue around the treatment area. When the tissue is to be treated, theone or more probes 672 may be projected from their respective openings670, as shown in FIG. 64B. The ablation probes 672 may be configured asa monopolar electrode assembly. FIG. 64C illustrates a perspective viewof an ablation catheter 666 configured as a bipolar probe including areturn electrode 674. Return electrode 674 may be positioned proximallyof probes 672, e.g., about 10 mm, along shaft 666.

In yet another variation, FIG. 65A shows a stabilizing sheath 14 whichmay be advanced through the inferior vena cava IVC, as above, in aflexible state. Once sheath 14 has been desirably positioned within theright atrium RA, its configuration may be optionally locked or securedsuch that its shape is retained independently of instruments which maybe advanced therethrough or independently of the motion of the heart.Such a locking configuration may be utilized via any number ofmechanisms as known in the art.

In either case, sheath 14 may have a stabilizing balloon 680, similar tothat described above, which may be expanded within the right atrium RAto inflate until the balloon 680 touches the walls of the chamber toprovide stability to the sheath 14, as shown in FIG. 65B. The tip of thesheath 14 may be farther advanced to perform a transseptal procedure tothe left atrium LA utilizing any of the methods and/or devices asdescribed in further detail in U.S. patent application Ser. No.11/763,399 filed Jun. 14, 2007, which has been incorporated above.

Once the sheath 14 has been introduced transseptally into the leftatrium LA, an articulatable section 682 may be steered as indicated bythe direction of articulation 684 into any number of directions, such asby pullwires, to direct the sheath 14 towards a region of tissue to betreated, such as the pulmonary vein ostium, as shown in FIG. 65C. Withthe steerable section 682 desirably pointed towards the tissue to betreated, the amount of force transmission and steering of the tissuevisualization catheter towards the tissue region is reduced andsimplified.

FIG. 65D shows illustrates an example of the telescoping capability ofthe deployment catheter 16 and hood 12 from the steerable sheath 14 intothe left atrium LA, as indicated by the direction of translation 686.Furthermore, FIG. 65E also illustrates an example of the articulatingability of the sheath 14 with deployment catheter 16 and hood 12extended from sheath 14, as indicated by the direction of articulation690. Deployment catheter 16 may also comprise a steerable section 688 aswell. With each degree of articulation and translation capability, hood12 may be directed to any number of locations within the right atrium RAto effect treatment.

FIGS. 66A and 66B illustrate yet another variation where sheath 14 maybe advanced transseptally at least partially along its length, as shownin FIG. 66A, as above. In this variation, rather than use of a singleintra-atrial stabilizing balloon, a proximal stabilization balloon 700inflatable along the atrial septum within the right atrium RA and adistal stabilization balloon 702 inflatable along the atrial septumwithin the left atrium LA may be inflated along the sheath 14 tosandwich the atrial septum AS between the balloons 700, 702 to providestabilization to the sheath 14, as shown in FIG. 66B. With sheath 14stabilized, a separate inner sheath 704 may be introduced from sheath 14into the left atrium LA. Inner sheath 704 may comprise an articulatablesection 706 as indicated by the direction of articulation 708 and asshown in FIG. 66C. Also, inner sheath 704 may also be translateddistally further into the left atrium LA as indicated by the directionof translation 710 to establish as short a trajectory for hood 12 toaccess any part of the left atrium LA tissue wall. With the trajectorydetermined by the articulation and translation capabilities, deploymentcatheter 16 may be advanced with hood 12 to expand within the leftatrium LA with a relatively direct approach to the tissue region to betreated, such as the ostium OT of the pulmonary veins, as shown in FIG.66E.

FIGS. 67A and 67B illustrate yet another variation where sheath 14 maybe advanced at least partially through the atrial septum AS and proximaland distal stabilization balloons 700, 702 may be expanded against theseptal wall. Similar to the variation above in FIGS. 62A to 62C, anintra-atrial balloon 660 may be expanded from the distal opening ofsheath 14 to expand and occupy a volume within the right atrium RA.Fiberscope 662 may be advanced at least partially within theintra-atrial balloon 660 to survey the cardiac chamber, as illustratedin FIG. 67C. Once a pulmonary vein ostium has been visually identifiedfor treatment, inner sheath 704 may be introduced from sheath 14 intothe left atrium LA and articulated and/or translated to direct itsopening towards the targeted tissue region to be treated. With atrajectory determined, a penetrating needle 720 having a piercing tip722 and a hollow lumen sufficiently sized to accommodate hood 12 anddeployment catheter 16, may be advanced from inner sheath 704 and intocontact against the balloon 660 to pierce through and access thetargeted tissue for treatment, as shown in FIGS. 67D and 67E. With thepiercing tip 722 extended into the pulmonary vein PV, penetrating needle720 may be withdrawn to allow for the advancement of hood 12 in its lowprofile shape to be advanced through the pierced balloon 660 or hood 12and deployment catheter 16 may be advanced distally through the lumen ofneedle 720 where hood 12 may be expanded externally of balloon 660. Withthe hood 12 deployed, catheter 16 may be retracted partially into innersheath 704 such that hood 12 occupies and seals the pierced openingthrough balloon 660. Hood 12 may also placed into direct contact withthe targeted tissue for treatment externally of balloon 660, asillustrated in FIG. 67F.

In utilizing the intra-atrial balloon 660, a direct visual image of theatrial chamber may be provided through the balloon interior. Because animager such as fiberscope 662 has a limited field of view, multipleseparate images captured by the fiberscope 662 may be processed toprovide a combined panoramic image or visual map of the entire atrialchamber. An example is illustrated in FIG. 68A where a first recordedimage 730 (represented by “A”) may be taken by the fiberscope 662 at afirst location within the atrial chamber. A second recorded image 732(represented by “B”) may likewise be taken at a second location adjacentto the first location. Similarly, a third recorded image 734(represented by “C”) may be taken at a third location adjacent to thesecond location.

The individual captured images 730, 732, 734 can be sent to an externalCPU via wireless technology such as Bluetooth® (BLUETOOTH SIG, INC,Bellevue, Wash.) or other wireless protocols while the tissuevisualization catheter is within the cardiac chamber. The CPU canprocess the pictures taken by monitoring the trajectory of articulationof the fiberscope or CCD camera, and process a two-dimensional orthree-dimensional visual map of the patient's heart chambersimultaneously while the pictures are being taken by the catheterutilizing any number of known imaging software to combine the imagesinto a single panoramic image 736 as illustrated schematically in FIG.68B. The operator can subsequently use this visual map to perform atherapeutic treatment within the heart chamber with the visualizationcatheter still within the cardiac chamber of the patient. The panoramicimage 736 of the heart chamber generated can also be used in conjunctionwith conventional catheters that are able to track the position of thecatheter within the cardiac chamber by imaging techniques such asfluoroscopy but which are unable to provide direct real timevisualization.

A potential complication in ablating the atrial tissue is potentiallypiercing or ablating outside of the heart H and injuring the esophagusES (or other adjacent structures), which is located in close proximityto the left atrium LA. Such a complication may arise when the operatoris unable to estimate the location of the esophagus ES relative to thetissue being ablated. In one example of a safety mechanism shown in FIG.69A, a light source or ultrasound transducer 742 may be attached to orthrough a catheter 740 which can be inserted transorally into theesophagus ES and advanced until the catheter light source 742 ispositioned proximate to or adjacent to the heart H. During anintravascular ablation procedure in the left atrium LA, the operator mayutilize the imaging element to visually (or otherwise such as throughultrasound) detect the light source 742 in the form of a background glowbehind the tissue to be ablated as an indication of the location of theesophagus ES. Different light intensities providing different brightnessor glow in the tissue can be varied to represent different safetytolerances, e.g., the stronger the light source 742, the easierdetection of the glow in the left atrium LA by the imaging element andpotentially greater safety margin in preventing an esophagealperforation.

An alternative method is to insert an ultrasound crystal source at theend of the transoral catheter instead of a light source. An ultrasoundcrystal receiver can be attached to the distal end of the hood 12 in theleft atrium LA. Through the communication between the ultrasound crystalsource and receiver, the distance between the ablation tool and theesophagus ES can be calculated by a processor. A warning, e.g., in theform of a beep or vibration on the handle of the ablation tools, canactivate when the source in the heart H approaches the receiver locatedin the esophagus ES indicating that the ablation probe is approachingthe esophagus ES at the ablation site. The RF source can also cut offits supply to the electrodes when this occurs as part of the safetymeasure.

Another safety measure which may be utilized during tissue ablation isthe utilization of color changes in the tissue being ablated. Oneparticular advantage of a direct visualization system described hereinis the ability to view and monitor the tissue in real-time and indetailed color. Thus, as illustrated in the side view of FIG. 69C, hood12 is placed against the tissue T to be ablated and any blood withinhood 12 is displaced with transparent saline fluid. Imaging element 532may provide the off-axis visualization of the ablation probe 536 placedagainst the tissue surface for treatment, as illustrated in FIG. 69B bythe displayed image of a representative real-time view that the userwould see on monitor 128. As the tissue is heated by ablation probe 536,represented by heated tissue 745 in FIG. 69E, the resulting color changeof the ablated tissue 744 may be detected and monitored on monitor 128as the ablated tissue 744 turns from a pink color to a pale white colorindicative of ablation or irreversible tissue damage, as shown in FIG.69D. The user may monitor the real-time image to ensure that anappropriate amount and location of tissue is ablated and is notover-heated by tracking the color changes on the tissue surface.

Furthermore, the real-time image may be monitored for the presence ofany steam or micro-bubbles, which are typically indications ofendocardial disruptions, emanating from the ablated tissue. If detected,the user may cease ablation of the tissue to prevent any further damagefrom occurring.

In another indication of tissue damage, FIGS. 69F and 69G show therelease of tissue debris 747, e.g., charred tissue fragments, coagulatedblood, etc., resulting from an endocardial disruption or tissue“popping” effect. The resulting tissue crater 746 may be visualized, asshown in FIG. 69F, as well as the resulting tissue debris 747. When thedisruption occurs, ablation may be ceased by the user and the debris 747may be contained within hood 12 and prevented from release into thesurrounding environment, as shown in FIG. 69G. The contained or captureddebris 747 within hood 12 maybe evacuated and removed from the patientbody by drawing the debris 747 via suction proximally from within hood12 into the deployment catheter, as indicated by the direction ofsuction 748 in FIG. 69H. Once the captured debris 747 has been removed,ablation may be completed upon the tissue and/or the hood 12 may berepositioned to treat another region of tissue.

Yet another method for improving the ablation treatment upon the tissueand improving safety to the patient is shown in FIGS. 69I to 69K. Thehood 12 may be placed against the tissue to be treated T and the bloodwithin the hood 12 displaced by saline, as above and as shown in FIG.69I. Once the appropriate tissue region to be treated has been visuallyidentified and confirmed, negative pressure may be formed within thehood 12 by withdrawing the saline within the hood 12 to create a suctionforce until the underlying tissue is drawn at least partially into thehood interior, as shown in FIG. 69J. The temporarily adhered tissue 749may be in stable contact with hood 12 and ablation probe 536 may beplaced into contact with the adhered tissue 749 such that the tissue 749is heated in a consistent manner, as illustrated in FIG. 69K. Once theablation has been completed, the adhered tissue 749 may be released andhood 12 may be re-positioned to effect further treatment on anothertissue region.

The applications of the disclosed invention discussed above are notlimited to certain treatments or regions of the body, but may includeany number of other treatments and areas of the body. Modification ofthe above-described methods and devices for carrying out the invention,and variations of aspects of the invention that are obvious to those ofskill in the arts are intended to be within the scope of thisdisclosure. Moreover, various combinations of aspects between examplesare also contemplated and are considered to be within the scope of thisdisclosure as well.

1. A tissue imaging and treatment system, comprising: a deploymentcatheter defining at least one lumen therethrough; a barrier or membraneprojecting distally from the deployment catheter and defining an openarea therein, wherein the open area is in fluid communication with theat least one lumen; a visualization element disposed within or along thebarrier or membrane for visualizing tissue adjacent to the open area;and an ablation energy transmitting surface positionable to ablatetissue adjacent to or contained within the open area.
 2. The system ofclaim 1 further comprising a delivery catheter through which thedeployment catheter is deliverable.
 3. The system of claim 1 wherein thedeployment catheter is steerable.
 4. The system of claim 3 wherein thedeployment catheter is steered via pulling at least one wire.
 5. Thesystem of claim 3 wherein the deployment catheter is steered viacomputer control.
 6. The system of claim 1 wherein the barrier ormembrane is comprised of a compliant material.
 7. The system of claim 1wherein the barrier or membrane defines a peripheral contact edge forplacement against a tissue surface so that the tissue surface spansalong and within the contact edge, wherein the energy transmittingsurface comprises an electrode electrically coupleable to the tissuesurface span for ablating the visualized tissue.
 8. The system of claim1 wherein the barrier or membrane is adapted to be reconfigured from alow-profile delivery configuration to an expanded deployedconfiguration.
 9. The system of claim 8 wherein the barrier or membraneis adapted to self-expand into the expanded deployed configuration. 10.The system of claim 8 wherein the barrier or membrane comprises one ormore support struts along the barrier or membrane.
 11. The system ofclaim 1 wherein the barrier or membrane is conically shaped.
 12. Thesystem of claim 1 wherein the visualization element comprises at leastone optical fiber, CCD imager, or CMOS imager.
 13. The system of claim 1wherein the visualization element is disposed within a distal end of thedeployment catheter.
 14. The system of claim 1 wherein the visualizationelement is articulatable off-axis relative to a longitudinal axis of thedeployment catheter.
 15. The system of claim 1 further comprising afluid reservoir fluidly coupled to the barrier or membrane.
 16. Thesystem of claim 15 wherein the fluid comprises saline, plasma, water, orperfluorinated liquid.
 17. The system of claim 1 wherein the barrier ormembrane further comprises a distal membrane extending over the openarea such that the energy transmitting surface comprises an ablationelectrode circumferentially disposed over the distal membrane.
 18. Thesystem of claim 1 wherein the barrier or membrane further comprises adistal membrane extending radially inwardly near a distal edge of thebarrier or membrane partially over the open area such that the distalmembrane defines an aperture through which the ablation electrode isextendable.
 19. The system of claim 1 wherein the energy transmittingsurface comprises an ablation electrode, and wherein the ablationelectrode is articulatable.
 20. The system of claim 1 wherein the energytransmitting surface comprises an ablation electrode, and wherein theablation electrode comprises a monopolar or bipolar radio-frequencyelectrode.
 21. The system of claim 1 wherein the energy transmittingsurface is reconfigurable from a first linear profile to a secondextended profile.
 22. The system of claim 21 wherein the second extendedprofile defines a linear configuration transverse relative to alongitudinal axis of the deployment catheter.
 23. The system of claim 21wherein the energy transmitting surface is contained within a linearhousing which is articulatable between a linear profile and an expandedY-shaped profile.
 24. The system of claim 21 wherein the second extendedprofile defines a circular configuration.
 25. The system of claim 1wherein the energy transmitting surface is circumferentially disposedover a contact lip or edge of the barrier or membrane.
 26. The system ofclaim 1 wherein the ablation probe comprises a plurality of needles. 27.The system of claim 26 wherein the plurality of needles is extendablefrom a retracted configuration into an ablation configuration.
 28. Thesystem of claim 1 further comprising an occlusion balloon which isexpandable into an inflated shape sufficiently sized to occlude a vessellumen.
 29. The system of claim 1 further comprising a firstarticulatable tissue grasper positioned upon a first support memberextending distally from the barrier or membrane.
 30. The system of claim29 further comprising a second articulatable tissue grasper positionedupon a second support member extending distally from the barrier ormembrane, wherein the second tissue grasper is articulatableindependently of the first tissue grasper.
 31. The system of claim 29further comprising a length of wire or suture slidably passed throughthe tissue grasper, wherein a first end of the wire or suture isattached to the tissue imaging and treatment system and a second end ofthe wire or suture is pulled from outside a patient body.
 32. The systemof claim 1 further comprising an intra-atrial balloon disposed upon adistal end of the catheter, wherein the balloon is expandable from alow-profile deflated configuration to an inflated configuration.
 33. Thesystem of claim 32 wherein the inflated configuration occupies up to 75%or more of volume of an atrial chamber within a patient heart.
 34. Thesystem of claim 32 wherein the intra-atrial balloon comprises one ormore radio-opaque markers.
 35. A tissue imaging and treatment system fortreating a tissue region within a heart, the heart having a chamber, thechamber including a tissue surface and containing blood, the systemcomprising: a catheter body having a lumen; a visualization elementdisposed adjacent the catheter body, the visualization element having afield of view; a translucent fluid source in fluid communication withthe lumen; and a barrier or membrane extendable from the catheter bodyto localize, between the visualization element and the field of view,displacement of blood by translucent fluid that flows from the lumen;and an ablation energy transmitting surface positionable for ablatingthe tissue within the field of view.
 36. The system of claim 35 whereinthe membrane or barrier is disposed about an open area between thevisualization element and the field of view, the fluid source configuredto inject translucent fluid so as to displace the blood from the openarea sufficiently to allow optical imaging of the tissue surface thoughthe open area while the heart is beating.
 37. The system of claim 36wherein the membrane is expandable from a low-profile deliveryconfiguration to an expanded configuration to encompass an imaged tissuesurface larger than a cross-section of the catheter.
 38. The system ofclaim 37 further comprises a frame supporting the membrane outside ofthe open area in the expanded configuration.
 39. The system of claim 38wherein the frame comprises a shape memory alloy, and wherein thevisualization element is supported by the frame.
 40. The system of claim35 wherein the barrier or membrane comprises a hood, the barrier ormembrane having a contact edge surrounding an aperture adjacent thefield of view so that, during use, transparent fluid from the lumen isreleased into the chamber of the heart through the aperture, wherein theenergy transmitting surface is translatable through the aperture. 41.The system of claim 35 wherein the barrier or membrane has an innersurface and an outer surface, a volume disposed within the inner surfacebeing greater than a volume disposed between the inner surface and theouter surface.
 42. The system of claim 35 wherein the catheter body isincluded in a steerable catheter, the steerable catheter having anelongate proximal portion and an articulable section adjacent thebarrier, the steerable section comprising a plurality of links andsteerable from a proximal end of the proximal portion so as to impose asmooth axial curvature on the catheter body.
 43. The system of claim 35wherein the catheter body has a working lumen slidably receiving theenergy transmitting surface, a lumen for receiving a steering element tolaterally deflect the catheter body, a translucent fluid flow lumen, andan image conduit for transmitting images of the tissue surface from thevisualization element.
 44. The system of claim 35 wherein the barrier ormembrane further comprises a distal membrane extending partially overthe open area such that the distal membrane defines an aperture throughwhich the energy transmitting surface is extendable.
 45. The system ofclaim 35 wherein the energy transmitting surface comprises anarticulatable ablation electrode.
 46. The system of claim 35 wherein theenergy transmitting surface comprises a monopolar or bipolarradio-frequency electrode.
 47. The system of claim 35 wherein the energytransmitting surface comprises a plurality of needles.
 48. The system ofclaim. 47 wherein the plurality of needles is extendable from aretracted configuration into an ablation configuration.
 49. The systemof claim 35 further comprising an occlusion balloon which is expandableinto an inflated shape sufficiently sized to occlude a vessel lumen. 50.The system of claim 35 further comprising a first articulatable tissuegrasper positioned upon a first support member extending distally fromthe barrier or membrane.
 51. The system of claim 50 further comprising asecond articulatable tissue grasper positioned upon a second supportmember extending distally from the barrier or membrane, wherein thesecond tissue grasper is articulatable independently of the first tissuegrasper.
 52. The system of claim 50 further comprising a length of wireor suture slidably passed through the tissue grasper, wherein a firstend of the wire or suture is attached to the tissue imaging andtreatment system and a second end of the wire or suture is pulled fromoutside a patient body.
 53. A method for intravascularly treating atissue region within a body lumen, comprising: positioning an open areaof a barrier or membrane against or adjacent to the tissue region to betreated; displacing an opaque bodily fluid with a translucent fluid froman open area defined by the barrier or membrane and the tissue region;visualizing the tissue region within the open area through thetranslucent fluid; and ablating at least a portion of the tissue regionwithin the open area.
 54. The method of claim 53 wherein positioning anopen area of a barrier or membrane comprises advancing the barrier ormembrane into a left atrial chamber of a heart.
 55. The method of claim53 wherein positioning an open area of a barrier or membrane comprisesdeploying the barrier or membrane from a low-profile deliveryconfiguration into an expanded deployed configuration.
 56. The method ofclaim 53 wherein positioning an open area of a barrier or membranecomprises stabilizing a position of the barrier or membrane relative tothe tissue region.
 57. The method of claim 53 wherein positioning anopen area of a barrier or membrane comprises steering the deploymentcatheter to the tissue region.
 58. The method of claim 53 whereindisplacing an opaque bodily fluid with a translucent fluid comprisesinfusing the translucent fluid into the open area through a fluiddelivery lumen defined through the deployment catheter.
 59. The methodof claim 58 wherein infusing the translucent fluid comprises pumpingsaline, plasma, water, or perfluorinated liquid into the open area suchthat blood is displaced from therefrom.
 60. The method of claim 53wherein displacing an opaque bodily fluid with a translucent fluidcomprises partially retaining the fluid within the open area via atleast one transparent distal membrane disposed at least partially over adistal end of the barrier or membrane.
 61. The method of claim 60wherein partially retaining the fluid comprises allowing the fluid toleak through at least one aperture defined through the distal membrane.62. The method of claim 61 wherein ablating comprises ablating thetissue region through the at least one aperture.
 63. The method of claim53 wherein visualizing the region of tissue comprises viewing the tissuevia an imaging element positioned off-axis relative to a longitudinalaxis of the barrier or membrane.
 64. The method of claim 53 whereinablating comprises contacting the tissue region with an ablation probeadvanced through the open area.
 65. The method of claim 64 furthercomprising articulating the ablation probe within the open area.
 66. Themethod of claim 53 wherein ablating comprises forming a linear orcircular lesion upon the tissue region.
 67. The method of claim 53further comprising occluding a blood flow through a pulmonary vein viaan occlusion balloon inflated within the pulmonary vein distal to thebarrier or membrane prior to ablating.
 68. The method of claim 53further comprising temporarily engaging a first and second tissue regionin an alternating manner such that the barrier or membrane is moved froma first location to a second location through the body lumen prior todisplacing an opaque bodily fluid.
 69. The method of claim 53 whereinablating comprises advancing a plurality of ablation needles into thetissue region.
 70. The method of claim 53 further comprising visuallymonitoring the tissue region for changes in color while ablating as anindication of sufficient tissue ablation.
 71. The method of claim 53further comprising visually monitoring the tissue region for indicationsof endocardiac disruptions.
 72. The method of claim 71 wherein if anendocardiac disruption is detected, adjusting a power of an ablationprobe or ceasing ablating the tissue region.
 73. The method of claim 72further comprising further visually inspecting the tissue region. 74.The method of claim 71 wherein if an endocardiac disruption occurs,containing any tissue debris released from the disruption within thebarrier or membrane.
 75. The method of claim 74 further comprisingsuctioning the tissue debris contained within the barrier or membraneproximally through the deployment catheter.
 76. The method of claim 53further comprising drawing the tissue region within the open area atleast partially into the barrier or membrane to create a seal betweentherebetween.
 77. The method of claim 76 wherein ablating comprisesablating the sealed tissue region within the open area.
 78. The methodof claim 53 further comprising visually inspecting a lesion formed uponthe tissue region within the open area.
 79. The method of claim 78further comprising repositioning the barrier or membrane upon a secondtissue region to treated.
 80. A method for treating a target tissue of aheart of a patient, the target tissue underlying an intracardiac hearttissue surface region within a chamber of the heart, the methodcomprising: optically imaging the tissue surface region; ablating thetarget tissue; and monitoring tissue response to the ablation using theoptical imaging while the heart is pumping blood.
 81. The method ofclaim 80 the heart of the patient having an arrhythmia, wherein theoptical imaging provides a system user sufficient feedback to verifycoupling between an energy transmitting surface and the tissue surfaceregion during formation of an ablation lesion such that the lesioninhibits the arrhythmia.
 82. The method of claim 81 wherein the energydelivery surface comprises an electrode surface, and wherein the systemuser can induce movement of the electrode surface or interrupts lesionformation in response to loss of contact between the target tissue andthe electrode surface during formation of the lesion.
 83. The method ofclaim 81 wherein the optical imaging feedback provided to the systemuser during formation of the lesion comprises changes in color along thetissue surface region, lesion-formation induced deformation along thetissue surface region, vaporization adjacent the tissue surface region,formation of bubbles adjacent the tissue surface region, positioning ofthe energy transmitting surface, movement of the energy transmittingsurface, and/or ablation debris.
 84. The method of claim 80 the heart ofthe patient having an arrhythmia, wherein the target tissue comprises anelongate lesion pattern, and wherein the optical imaging provides asystem user sufficient feedback to verify contiguity along a length ofthe lesion pattern such that the lesion pattern inhibits propagation ofthe arrhythmia.
 85. The method of claim 84 wherein the lesion patterncomprises a plurality of discrete ablation lesions formed sequentiallyin the target tissue, and wherein a movement of an energy transmittingsurface from alignment with a first portion of the target tissue to asecond portion of the target tissue is performed using optical feedbackfrom the tissue response along a first discrete lesion associated withthe first region of the target tissue.
 86. The method of claim 84wherein the lesion pattern is formed by moving an energy transmittingsurface relative to the tissue surface region while transmitting energyfrom the energy transmitting surface to the target tissue, and whereinthe movement is performed using optical feedback on progress of thetissue response along the length of the lesion pattern.
 87. The methodof claim 84 wherein the optical imaging feedback provided to the systemuser during formation of the lesion comprises changes in color along thetissue surface region, lesion-formation induced deformation along thetissue surface region, vaporization adjacent the tissue surface region,formation of bubbles adjacent the tissue surface region, positioning ofthe energy transmitting surface, movement of the energy transmittingsurface, and/or ablation debris.
 88. The method of claim 80 furthercomprising interrupting the ablating of the target tissue during theablation in response to optical indicia of a potential tissue surfacedisruption, wherein the ablation is interrupted prior to embolization ofablation debris or bursting along the tissue surface region.
 89. Themethod of claim 81 further comprising cooling the imaged tissue surfaceregion during the imaging and the ablation.
 90. The method of claim 80wherein the tissue surface region is imaged by locally displacing bloodfrom an imaging volume within the chamber of the heart.
 91. The methodof claim 90 wherein the translucent fluid comprises a transparent fluid,wherein the chamber of the heart pumps blood disposed around the imagingvolume, and wherein-the transparent fluid is in contact with the tissuesurface region.
 92. The method of claim 91 wherein the transparent fluidflows along the tissue surface region so as to purge blood from betweenthe energy transmitting surface and the tissue surface region.
 93. Themethod of claim 92 wherein the transparent fluid cools the tissuesurface region.
 94. The method of claim 91 further comprisingintroducing a barrier or membrane into the chamber, expanding thebarrier or membrane within the chamber, and limiting intrusion of theblood from within the chamber into the imaging volume with the barrieror membrane during the imaging.
 95. The method of claim 80 wherein theoptical imaging is performed so as to image a plurality of anatomicallandmarks, and further comprising aligning the energy delivery surfacewith the target tissue in response to an image of one or more of theimaged landmarks.
 96. The method of claim 80 wherein the anatomicallandmarks comprise a pulmonary vein, an ostium of the pulmonary vein, aleft atrial septum, a left atrial appendage, a mitral valve, a tricuspidvalve, a fossa ovalis and a right atrial appendage.
 97. A system fortreating a target tissue of the heart of a patient, the target tissueunderlying an intracardiac heart tissue surface region within a chamberof the heart, the method comprising: an intracardiac catheter having aproximal end, a distal end, and at least one lumen; an optical imagingelement advanceable distally using the catheter into the chamber of theheart; an energy transmitting surface advanceable distally using thecatheter into alignment with the tissue surface region for ablation ofthe target tissue; and an imaging fluid flow path extendable distallyfrom a translucent fluid source, through the catheter, and toward thetissue surface region, the extended flow path encompassing the opticalimaging element and the aligned energy transmitting surface so as toinhibiting persistence of blood within a field of view of the imagingelement when optically directing the ablation while the heart is pumpingthe blood.